Reclosable packaging

ABSTRACT

Touch fasteners useful for bags, packaging and other products as well as novel manufacturing of products incorporating such fasteners. A composite touch fastener has a fibrous loop strip partially encapsulated in, or otherwise permanently attached to, resin of a substrate, and an array of loop-engageable fastener elements integrally molded with resin of the substrate. The center portion of the closure seals the bag until it is torn away to expose the mating bands of loops and fastener elements. Methods of applying recloseable touch fasteners, e.g. hook and loop fasteners, to sheet or film include vertical form and fill and horizontal form and fill packaging and pouch making.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of PCT Patent ApplicationSer. No. PCT/US99/26261, filed Nov. 5, 1999, revived by petition filedon Apr. 9, 2003, which is a continuation-in-part of U.S. patentapplication Ser. No. 09/187,389, filed Nov. 6, 1998, now U.S. Pat. No.6,202,260. PCT Patent Application Ser. No. PCT/US99/26261 claims thebenefit of U.S. Provisional Patent Application Ser. No. 60/159,489,filed Oct. 14, 1999 and also claims the benefit of U.S. ProvisionalPatent Application 60/228,819, filed Apr. 16, 1999, which was convertedto a Provisional Patent Application from a Utility application Ser. No.09/293,257.

TECHNICAL FIELD

This invention relates generally to touch fasteners, such as compositetouch fasteners having both loops and loop-engageable fastener elementsextending from one side of a common substrate, to their application inproducts such as closure strips for reclosable bags, and to methods andapparatus for their manufacture and incorporation into bags.

BACKGROUND

There has been much development over the last thirty years in the fieldof hook-and-loop fasteners. Early touch fastener products of this typeconsisted of two mating tapes, each being knit or woven. One tape wouldinclude loops of filament woven into a base, and the other would includefilaments woven to form loops and then cut to form hooks. In some casesfree ends of drawn plastic filaments on the male tape would be melted toform protruding heads. This shape of fastener element is sometimescalled a “mushroom”, to distinguish it from “hook”-shaped elements withre-entrant crooks. In some cases, arrays of similar discrete fasteningelements on two parts are shaped to engage with each other to form areleasable closure, these being known as “self-engageable” hooks orclosures.

More recently, continuous molding of fastener elements extending from acommon sheet-form resin base has resulted in less expensive and thinnermale tapes. Significant improvements in this area include thedevelopment of continuous fastener tape molding using fixed moldcavities (see Fischer, U.S. Pat. No. 4,794,028), and the ability toprovide loops on the back side of the male fastener tape as the fastenertape substrate and elements are being formed (see Kennedy et al., U.S.Pat. No. 5,260,015), thus creating a composite fastener tape capable offastening to itself. Further improvements have reduced the size of thefastener elements moldable by such techniques, to heights of 0.015 inchor less, which provide a very smooth touch when arranged in densearrays.

Another example of molded fastener tape involves molding perform stemsor similar structures integral with a plastic backing substrate, andthereafter performing a forming operation to convert outer portions to aJ hook, a mushroom head or similar engaging structure.

As molded fastener tape has been improved to be more flexible and lessexpensive, it has found application in disposable garments, such asdiapers. Further improvements are desirable to extend the applicabilityof molded touch fastener products to other uses.

One such use that is discussed in more detail below is as a closure forreclosable bags and other such packaging.

Other types of repeated use closures for bags have included, forinstance, rib-and-groove type of locking or zipper closures such as aremarketed under the name ZIPLOC. These have very different fasteningcharacteristics and exacting requirements for joining to sheet or filmin comparison to touch-fastener closures. For example, on zipper style(interlocking rib and groove) products, in order to maintain alignmentand the integrity of the seal once it is closed, the ends of such aclosure are required to be permanently closed and sealed, to provide abeginning point for effecting closure. Other limitations relating tomanufacture and use are also known.

SUMMARY

The invention features, in several of its aspects, a composite touchfastener product having both a band of loops and a band of hooksextending from a single face of a common, sheet-form substrate. Amongother applications, this product can be included at the opening of a bagto function as a repeated use closure.

According to one aspect of the invention, an elongated closure stripincludes a sheet-form resin substrate having a front face and a backface, an array of loop-engageable fastener elements with stemsintegrally molded with and extending from the front face of thesubstrate and forming a discrete band of fastener elements extendinglongitudinally along the length of the closure strip, and a loop stripcarried on the front face of the substrate and forming a discrete bandof engageable loops extending along the length of the closure strip andspaced apart from the band of fastener elements. The loop strip isarranged to be engaged by the array of fastener elements when thesubstrate is folded along a fold line extending between the loop stripand the array of fastener elements. The substrate defines at least onefrangible region extending longitudinally along the length of theclosure strip between the band of loops and the band of fastenerelements, for tearing the substrate between the loops and the fastenerelements, to open an associated bag, the frangible region comprising anembedded longitudinally continuous filament adapted to be torn from theclosure strip to tear the substrate along the frangible region.

In some embodiments, the filament is completely enclosed within alongitudinal rib integrally molded with and extending from the substratebetween the band of loops and the band of fastener elements. Thelongitudinal rib enclosing the filament may be disposed on the back faceof the substrate, for example.

In some cases, the fastener elements have distal ends integrally moldedwith their stems and the front face of the substrate.

The substrate of some embodiments of the closure strip is advantageouslyformed of the same material as the substrate, e.g. enabling welding thesubstrate to the bag material. Such material can for instance bepolypropylene, polyester or nylon, chosen for their excellent barrierqualities (as well as polyethylene which has poor barrier qualities),and copolymers and compatible mixtures that include at least one of suchresins.

Some embodiments of the closure strip also include an adhesive stripcarried on the front face of the substrate between the band of fastenerelements and the band of loops. The adhesive strip has an exposedsurface arranged to contact the front face of the closure strip when theclosure strip is folded to engage the loops with the fastener elements,to retain the closure strip in a folded state.

Alternatively, some embodiments have a first adhesive strip carried onthe front face of the substrate between the band of fastener elementsand the pair of grooves, and a second adhesive strip carried on thefront face of the substrate between the band of loops and the pair ofgrooves. The first and second adhesive strips have exposed surfacesarranged to contact each other when the closure strip is folded toengage the loops with the fastener elements, to retain the closure stripin a folded state. In either case, these adhesive strips canadvantageously provide an air-tight seal when the closure is closed.

In some cases the closure strip includes a strip of peelable adhesivecarried on the front face of the substrate for providing a peelable sealacross the opening of an associated bag. For some applications the stripof peelable adhesive is disposed between a longitudinal edge of theclosure strip and both of the bands of fastener elements and loops. Insome other applications the strip of peelable adhesive is disposedbetween the bands of fastener elements and loops.

In some embodiments, the closure strip includes a layer of paperpermanently adhered to the substrate. In some cases, this layer of paperis carried on the front face of the substrate, in its longitudinal edgeregions. In some cases, the paper is carried on the back face of thesubstrate. In some other cases, the layer of paper is disposed between acenter region of the loop strip and the substrate.

In some cases the resin of the sheet or film packaging material or theresin of the backing substrate of a closure strip to be joined to thepackaging material, or both, includes an additive in the resin blend ora discrete outer layer, as by coextrusion, of a material thatcontributes to weldability of the matching surfaces. Such additivesinclude for instance an ionomer such as marketed by duPont under themark Surlyn™, or an ethylene vinyl acetate (EVA) additive which lowersthe weld temperature, or a material known as metalocene which is used tosharpen or adjust the melting range of materials to be welded together.

According to another aspect of the invention, a reclosable bag includesa bag body having two opposing side walls joined along three edges toform between them a pouch having an open end, and a closure strippermanently attached to the two side walls of the bag body along theopen end. The closure strip includes a sheet-form resin substrate havinga front face and a back face, an array of loop-engageable fastenerelements with stems integrally molded with and extending from the frontface of the substrate and forming a discrete band of fastener elementsextending longitudinally along the length of the closure strip, and aloop strip carried on the front face of the substrate and forming adiscrete band of engageable loops extending along the length of theclosure strip and spaced apart from the band of fastener elements. Theloop strip is arranged to be engaged by the array of fastener elementsto releasably retain the bag in a closed condition. The substrate of theclosure strip defines at least one frangible region extendinglongitudinally along the length of the closure strip between the band ofloops and the band of fastener elements, for tearing the substratebetween the loops and the fastener elements to open the bag, and thefrangible region includes an embedded, longitudinally continuousfilament adapted to be torn from the closure strip to tear the substratealong the frangible region.

In some embodiments, the filament is fully enclosed within alongitudinal rib extending from the back face of the substrate of theclosure strip and disposed inside the bag.

The filament, in some instances, has an end attached to a pull tabextending from one edge of the bag.

In some configurations, the bag defines a slit through an edge region ofthe bag but not extending into the interior of the bag, the slitdefining a graspable pull tab within the edge region and containing anend of the filament.

In some cases, the pull tab is defined between a pair of slits on eitherside of the filament and extending through an adjacent edge of the bag.

According to another aspect of the invention, a reclosable bag includesa bag body having two opposing side walls joined along three edges toform between them a pouch having an open end, and a closure strippermanently attached to the two side walls of the bag body along theopen end. The closure strip includes a sheet-form resin substrate havinga front face and a back face, an array of loop-engageable fastenerelements with stems integrally molded with and extending from the frontface of the substrate and forming a discrete band of fastener elementsextending longitudinally along the length of the closure strip, and aloop strip carried on the front face of the substrate and forming adiscrete band of engageable loops extending along the length of theclosure strip and spaced apart from the band of fastener elements. Theloop strip is arranged to be engaged by the array of fastener elementsto releasably retain the bag in a closed condition. A second array ofloop-engageable fastener elements has stems integrally molded with andextending from the back face of the substrate and forms a second band offastener elements extending longitudinally along the outer surface ofthe bag, for hanging the bag for display.

In some instances, the closure strip further comprises a second loopstrip carried on the back face of the substrate and forming a seconddiscrete band of engageable loops extending along the outer surface ofthe bag, for hanging the bag for display.

According to another aspect of the invention, a reclosable bag includesa bag body having two opposing side walls joined along three edges toform between them a pouch having an open end, and a closure strippermanently attached to the two side walls of the bag body along theopen end. The closure strip includes a sheet-form resin substrate havinga front face and a back face, an array of loop-engageable fastenerelements with stems integrally molded with and extending from the frontface of the substrate and forming a discrete band of fastener elementsextending longitudinally along the length of the closure strip, and aloop strip carried on the front face of the substrate and forming adiscrete band of engageable loops extending along the length of theclosure strip and spaced apart from the band of fastener elements. Theloop strip is arranged to be engaged by the array of fastener elementsto releasably retain the bag in a closed condition. Particularly, thefront face of the closure strip forms an outer surface of the bag, withthe bands of loops and fastener elements carried on the outer surface ofthe bag.

In some instances, both the band of loops and the band of fastenerelements are disposed on a front side of the bag, such that the fastenerelements engage the loops when an adjacent edge of the bag is foldedover.

In some cases, the substrate of the closure strip defines a frangibleregion between the bands of loops and fastener elements, the frangibleregion running along one side of the bag and configured to be torn toopen the bag. The frangible region may be configured to be torn byapplying a transverse tensile load across the frangible region, such asby being weaker with respect to a transverse tensile load than the sidewalls of the bag and the attachment between the side walls of the bagand the bag closure.

In some configurations, the side wall forming the front side of the baghas an exposed tab for grasping and pulling the front side of the bag totear the frangible region of the closure strip. The tab may extendacross the front side of the bag.

In some embodiments, the bands of loops and fastener elements aredisposed on opposite sides of the bag, such that the fastener elementsengage the loops when an adjacent edge of the bag, formed by a fold inthe closure strip, is folded over twice. In some cases, with the closurestrip is folded over twice, adjacent layers of the substrate togetherform a barrier to fluids.

According to another aspect of the invention, a reclosable bag includesa bag body having two opposing side walls joined along three edges toform between them a pouch having an open end, and a closure strippermanently attached to the two side walls of the bag body along theopen end. The closure strip includes a sheet-form resin substrate havinga front face and a back face, an array of loop-engageable fastenerelements with stems integrally molded with and extending from the frontface of the substrate and forming a discrete band of fastener elementsextending longitudinally along the length of the closure strip, and aloop strip carried on the front face of the substrate and forming adiscrete band of engageable loops extending along the length of theclosure strip and spaced apart from the band of fastener elements. Theloop strip is arranged to be engaged by the array of fastener elementsto releasably retain the bag in a closed condition. Particularly, thesubstrate of the closure strip carries printed indicia visible fromoutside the bag.

According to another aspect of the invention, a reclosable bag includesa bag body having two opposing side walls joined along three edges toform between them a pouch having an open end, and a closure strippermanently attached to the two side walls of the bag body along theopen end. The closure strip includes a sheet-form resin substrate havinga front face and a back face, an array of loop-engageable fastenerelements with stems integrally molded with and extending from the frontface of the substrate and forming a discrete band of fastener elementsextending longitudinally along the length of the closure strip, and aloop strip carried on the front face of the substrate and forming adiscrete band of engageable loops extending along the length of theclosure strip and spaced apart from the band of fastener elements. Theloop strip is arranged to be engaged by the array of fastener elementsto releasably retain the bag in a closed condition. Particularly, thesubstrate of the closure strip defines a hole forming a graspable handlefor carrying the bag.

According to another aspect of the invention, a continuous sheet-formproduct useful for forming bags, includes a continuous sheet-form filmand a length of closure strip permanently bonded to the film. Theclosure strip includes a sheet-form resin substrate having an exposedfront face, a loop strip carried on the front face of the substrate andcomprising a discrete band of hook-engageable loops extending along thelength of the closure strip, and an array of loop-engageable fastenerelements with stems integrally molded with resin of the front face ofthe substrate and forming a discrete band of fastener elements extendinglongitudinally along the length of the closure strip and spaced apartfrom the band of loops.

In some cases, the closure strip is continuous and extends along thefilm centerline. In some other cases, the closure strip extends alongone edge of the film.

In some embodiments, the closure strip extends transversely across thefilm.

According to another aspect of the invention, a continuous sheet-formproduct useful for forming bags includes a continuous sheet-form filmand multiple lengths of closure strip extending transversely across thefilm at spaced intervals and permanently bonded to the film. Eeachlength of closure strip has two overlapping substrates, each substratebonded separately to the bag film on opposite sides of an associatedfrangible region of the film, a loop strip carried on the front face ofthe first substrate and comprising a discrete band of engageable loopsextending along the length of the closure strip, and an array ofloop-engageable fastener elements extending from the second substrateand forming a discrete band of fastener elements extendinglongitudinally along the length of the closure. The first and secondsubstrates are overlapped as bonded to the film, such that the bands ofloops and fastener elements overlap for engagement.

In some embodiments, the fastener elements have stems integrally moldedwith resin of the front face of the second substrate.

According to another aspect of the invention, a method of fabricating aclosure strip includes molding a continuous, sheet-form substrate havinga band of fastener elements with stems integrally molded with andextending from a front face of the substrate, attaching a continuousstrip of loop material to resin forming the front face of the substrateto form a discrete band of loops spaced apart from the band of fastenerelements, and embedding a longitudinally continuous filament in resin ofthe substrate.

In some embodiments, the filament is completely enclosed by resin of arib extending from one face of the substrate.

According to another aspect of the invention, a method of fabricatingreclosable bags includes providing a continuous length of sheet-form bagwall material, providing a continuous closure strip, permanentlyattaching the closure strip along the sheet-form bag wall material toform a continuous length of preform bag material, and forming individualbags from the preform bag material. The closure strip includes asheet-form resin substrate having a front face, a loop strip carried onthe front face of the substrate and forming a discrete band ofengageable loops along the length of the closure strip, and an array ofloop-engageable fastener elements with stems integrally molded with thefront face of the substrate and forming a discrete band of fastenerelements extending longitudinally along the length of the closure stripand spaced apart from the band of loops.

In some cases, the step of attaching produces a preform tube of bagmaterial, and the steps of attaching and forming are performedsimultaneously in a vertical form and fill process, with the individualbags containing a predetermined quantity of material to be stored in thebags.

In some applications, the closure strip is attached to longitudinaledges of the sheet-form plastic to form a fin seal of the preform tube.

In some embodiments, the closure strip is folded to form a foldextending outward, away from the preform tube, such as with the folddefining a distal edge of the fin seal.

In some other embodiments, the closure strip is folded to form a foldextending inward, toward the preform tube.

In some cases, the step of attaching produces, a preform tube of bagmaterial, and the steps of attaching and forming are performedsimultaneously in a horizontal form and fill process, with theindividual bags formed about associated packages of material.

In some embodiments, longitudinal edges of the bag side wall materialare brought together to form a fin seal with the closure strip foldedlongitudinally and disposed within the fin seal, or with the closurestrip folded longitudinally about and attached to the longitudinal edgesof the bag side wall material.

In some applications, the step of attaching includes folding the closurestrip along its length to engage the bands of loops and fastenerelements in an engagement zone, the loops and fastener elements holdingtheir underlying regions of the substrate in spaced apart relation. Thestep of attaching may include welding the bag side wall material to theback face of the substrate, the engagement zone providing a heat barrierto inhibit permanently welding the substrate together in its foldedcondition.

In some instances, the step of forming includes folding the preform bagmaterial along its centerline, and then forming transverse seals spacedalong the preform bag material at bag length intervals to form a chainof open-ended bags. The closure strip may be attached along the bag sidewall material between longitudinal edges of the material, with thepreform bag material being subsequently folded at the closure strip toengage the bands of loops and fastener elements.

In some cases, the step of attaching includes individually folding thebag side wall material and the closure strip, and then joining thefolded wall material and closure strip along their longitudinal edges toform a continuous tube of preform bag material. The step of forming mayinvolve creating transverse seals across the tube of preform bagmaterial to form a series of discrete, empty bags.

The bag side wall material may be provided as two separate materialsheets, with the step of attaching including attaching the closure stripto one longitudinal edges of each sheet, such that the preform bagmaterial comprises the two material sheets joined at the closure strip,and the step of forming individual bags involving forming transverseseals across the preform bag material and joining the other longitudinaledges of the sheets of material to form a series of sealed bags.

In some cases the closure strip contains an embedded pull cord, with thestep of forming including forming a graspable pull tab extending from anedge of each bag, the pull tab containing an end of the pull cord. Thegraspable pull tab may be formed by slitting each bag in a side sealarea thereof, with the slitting cutting through the pull cord but notextending into the interior of the bag. In some applications, theslitting forms two slits extending from an adjacent edge of the bag tothe filament.

According to another aspect of the invention, a method of fabricatingreclosable bags in a vertical form and fill process includes unrolling acontinuous length of sheet-form bag film and directing the unrolled filmover a forming head, advancing the bag film one bag length betweenpauses, and forming individual bags from the bag film, each bag havingan associated length of closure strip. During each pause, a length ofclosure strip is attached across the unrolled bag film upstream of theforming head. Each length of closure strip includes a sheet-form resinsubstrate having a front face, a loop strip carried on the front face ofthe substrate and forming a discrete band of engageable loops along thelength of the closure strip, and an array of loop-engageable fastenerelements with stems integrally molded with the front face of thesubstrate and forming a discrete band of fastener elements extendinglongitudinally along the length of the closure strip and spaced apartfrom the band of loops.

In some embodiments, the loop strip comprises a non-woven web ofentangled fibers forming the loops and having a basis weight of lessthan about 4 ounces per square yard (preferably, less than about 2ounces per square yard). In some cases, the non-woven web comprises aneedled web in a stretched condition.

In some embodiments, fibers of the loop strip are affixed to thesubstrate across the width of the loop strip, such as by beingencapsulated by resin of the substrate. By “width” of the loop strip, wemean the entire transverse dimension of the preformed strip, as measuredbetween the outermost edges of the preformed strip before it is attachedto the substrate.

In many cases, the loop strip has a fiber density which is substantiallyconstant across its width, yet the loop strip has discrete regions whichare more encapsulated by resin than other regions of the loop strip.These discrete, more encapsulated regions may be spaced apartlongitudinally along the loop strip, extend lengthwise along the loopstrip and be spaced apart widthwise, or be arranged in a checkerboardpattern, for instance.

When we refer to regions of the loop strip as being more “encapsulated”than other regions, we mean that the fibers of the more encapsulatedregions are generally more thoroughly embedded in the resin of thesubstrate than the fibers of other regions. Generally, this will involvea deeper penetration of the substrate resin into the loop strip.

In some embodiments, longitudinal edge regions of the loop strip areaffixed to the substrate, while a center region (between the edgeregions) is substantially loose from the substrate. The center region ofthe loop strip may advantageously define a gentle arc extending awayfrom the substrate in some of these embodiments.

In some configurations, a barrier layer (of a different material thanthe substrate) is included between the substrate and the loop strip.This barrier layer may be of paper or a polymer resin, for example.

In some cases the loop strip has at least one edge which issubstantially loose from the substrate. This edge may be either an inneror outer edge in a finished bag, and can help to redirect peelseparation forces to enhance the peel strength of the fastening.

In some closure strips, open-ended pockets are defined between an edgeof the loop strip and the substrate. These pockets can also help toenhance peel strength in some cases.

In some embodiments, the edge regions of the loop strip have fibersdirectly encapsulated within resin of the substrate, while the closurestrip also includes a binder (of a different material than thesubstrate) connecting fibers of the center region (between the edgeregions) of the loop strip to resin of the substrate.

In some embodiments, the substrate defines a pair of grooves extendinglongitudinally along the length of the closure strip between the band ofloops and the band of fastener elements. These grooves may be lengthwisecontinuous and defined by molded surfaces in the front face of thesubstrate.

The closure strip also includes, in some cases, a longitudinal ribintegrally molded with and extending from the front face of thesubstrate between the band of loops and the band of fastener elements.In some of these cases, the rib is disposed between the pair of groovesjust described.

In some embodiments, the front face of the substrate has twolongitudinal edge regions void of fastener elements and loops, forpermanently adhering the substrate to the sides of a bag. These edgeregions may be covered with a layer of adhesive for permanentlyattaching the closure strip to opposite sides of a bag, or compriseexposed resin of the substrate, for permanently welding the closurestrip to opposite sides of a bag formed of a compatible material. Theselongitudinal edge regions may alternatively be disposed on the back faceof the substrate.

The substrate of some embodiments of the closure strip is advantageouslyformed of polyethylene, such as for welding the substrate topolyethylene bag material.

Some embodiments of the closure strip also include an adhesive stripcarried on the front face of the substrate between the band of fastenerelements and the band of loops. The adhesive strip has an exposedsurface arranged to contact the front face of the closure strip when theclosure strip is folded to engage the loops with the fastener elements,to retain the closure strip in a folded state.

Alternatively, some embodiments have a first adhesive strip carried onthe front face of the substrate between the band of fastener elementsand the pair of grooves, and a second adhesive strip carried on thefront face of the substrate between the band of loops and the pair ofgrooves. The first and second adhesive strips have exposed surfacesarranged to contact each other when the closure strip is folded toengage the loops with the fastener elements, to retain the closure stripin a folded state. In either case, these adhesive strips canadvantageously provide an air-tight seal when the closure is closed.

In some embodiments, the closure strip includes a layer of paperpermanently adhered to the substrate. In some cases, this layer of paperis carried on the front face of the substrate, in its longitudinal edgeregions. In some cases, the paper is carried on the back face of thesubstrate. In some other cases, the layer of paper is disposed between acenter region of the loop strip and the substrate.

According to a second aspect of the invention, an elongated closurestrip includes a sheet-form resin substrate having front and back faces,a loop strip carried on the front face of the substrate, and an array ofloop-engageable fastener elements carried on the front face of thesubstrate. The loop strip forms a discrete band of hook-engageable,free-standing loops along the length of the closure strip, and the arrayof fastener elements forms a discrete band of fastener elementsextending longitudinally along the length of the closure strip andspaced apart from the band of loops. The substrate defines a pair ofgrooves extending longitudinally along the length of the closure stripbetween the band of loops and the band of fastener elements, and alongitudinal rib integrally molded with and extending from the substratebetween the pair of grooves.

In some embodiments, the loop strip comprises a non-woven web ofentangled fibers forming the loops and having a basis weight of lessthan about 4 ounces per square yard (preferably, less than about 2ounces per square yard).

In some cases, the grooves and rib are disposed on the front face of thesubstrate. In other cases, they are disposed on its back face.

Preferably, the fastener elements are integrally molded with resin ofthe substrate.

In some cases, the strip of loop material has regions of substantiallyhigher loft than regions corresponding to the discrete regions which aresubstantially more encapsulated by resin. By “loft”, we mean thedistance the exposed loops of the loop material extend from the frontface of the substrate, as presented for engagement by fastener elements.

Some aspects of the invention feature a bag closure having matable touchfastener elements arranged in parallel strips extending from an outersurface of a bag. Between the strips of fastener elements is a frangibleregion adapted to be torn apart to initially open the bag. After initialopening, the bag is reclosed by folding the closure about the tornfrangible region to engage the strips of matable fastener elements.

In some embodiments, one of the strips of fastener elements is a band ofhook-engageable loops or fibers, the other strip being of extending malefastener elements, such as hooks or mushrooms.

In some other embodiments, the strips are of self-engageable malefastener elements, having arrays of spaced-apart elements that aredesigned to interlock, for example, when pressed together.

Preferably, the closure is a continuous, thin, strip-form extrusion ofplastic material upon one face of which the fastener elements are eitherintegrally molded of material of the extrusion or bonded to theextrusion while the extrusion is in a softened state, such that thefastener elements are joined directly to the extruded material, or areformed out of the extruded material, without separate adhesives orbonding agents.

The frangible zone may be, for instance, a channel formed in one face ofthe extruded material between the strips of fastener elements. Thechannel may be either on the outer or inner face of the closure, asincorporated into a bag.

Joined with bag material to form a bag, the closure is preferablyarranged such that the frangible zone extends parallel to and adjacentone edge of the bag. By adjacent, we mean that the frangible zone ispreferably between one-half and two inches from the bag edge, such thatsufficient space is provided between the frangible zone and the bag edgeto grasp the edge region of the bag with one hand while, with the otherhand, the main body of the bag is pinched, on the other side of thefrangible zone, and pulled away from the frangible zone to tear theclosure along the frangible zone.

In one preferred bag construction, the bag material forming the backface of the bag is permanently bonded to the back surface of the closurealong one closure edge, and the bag material forming the front face ofthe bag is permanently bonded to the front face of the closure along itsopposite edge, in an edge bonding zone free of fastener elements.

As an alternative to pinching the main body of the bag to separate theclosure along its frangible zone, a pull flap may be provided at theconnection of the closure to the bag material forming the front face ofthe bag. The pull flap may either be in the form of a loose edge of thebag material not joined to the closure but exposed along the closure tobe grasped and pulled, or a discrete, local flap of bag material formed,for instance, by die-cutting the bag material prior to attaching theclosure.

In one embodiment, the closure is formed of polyethylene and has anominal thickness of about 0.004 inch (0.1 millimeter). The frangiblezone is a groove in which the thickness of the closure is reduced toabout 0.002 inch (0.05 millimeter) over a groove width of about 0.036inch (0.9 millimeter). Such a construction can provide acceptable tearproperties when incorporated into a bag otherwise formed of 0.002 to0.005 inch thick (0.05 to 0.125 millimeter thick) polyethylene, forexample.

In another embodiment, the frangible zone includes a pull rib which isdesigned to be pulled along the closure from one edge of the bag to theopposite bag edge, thereby tearing the closure between the strips offastener elements. In such embodiments, the pull rib may be exposed forgrasping by forming a hole or notch through the bag material of the backface of the bag extending partially across the width of the side seal ofthe bag, immediately behind the pull rib. With the back face of the bagrelieved or otherwise spaced apart from the end of the pull rib, the endof the pull rib can be readily grasped and pulled along the width of thebag to initially open the closure.

According to further aspects of the invention, methods of applying areclosable fastener to sheet or film are provided, which include thesteps of providing inter-engageable closure strip portions which areeither separate strips or strip portions of a common member and joiningthe backing of the strip portions to respective portions of the surfaceof the sheet or film by application of energy such as heat, acoustic orradio-frequency energy, to produce for instance welding or adhesivebonding. At least a first of the closure strip portions provides anarray of discrete fastener elements such as hook elements having crooksor hook elements having mushroom form, the fastener elements havingstems integrally molded with and extending from a thermoplastic backingsubstrate. The other of the strip portions provides an array ofengageable elements such as hook-engageable loops or fibers, or elementsself-engageable with fastener elements of the first strip portion, suchthat the discrete elements of the strip portions are capable of forminga releasable closure. In one aspect, during joining, the fastenerelements of the respective strip portions are inter-engaged and thebackings of the strip portions are simultaneously joined to respectiveportions of the sheet or film by application of energy to the respectivesheet or film portions, with insulating air pockets provided in thespace created by the inter-engaged elements serving to limit thermaltransfer and unwanted adhesion or bonding of the closure portions toeach other.

In another aspect, the cooperating parts of the releasable closure areof materials that are incompatible or of significantly different meltingtemperatures such that, under temperature conditions of joining, theinterengaged elements do not tend to adhere to each other. Suchprovisions can avoid the need for presence of a release sheet during thejoining action.

In one example, loops or fibers of the second strip portion areencapsulated by and secured by thermoplastic resin of the backing of therespective closure strip portion, the loops or fibers being comprised ofresin, such as polyester, that is incompatible with or has a highermelting temperature than the resin such as polyolefin, of the respectivebacking substrate, and/or of components of the opposed first stripportion, such that, under conditions of joining, the dissimilarity ofthe material of the loops or fibers serves to prevent detrimental changeto the loops or fibers or detrimental adhesion or bonding of the loopsor fibers to the first closure strip portion, preferably, the mass ofthe hook elements of the first portion being substantially greater thanthat of the loop elements, the thermal mass of the hook elements beingsufficient to prevent undue distortion of the hooks during the joiningaction.

The methods described herein are advantageously applicable to bothvertical form and fill packaging and horizontal form and fill packaging,as examples. The method is also employed to advantage during pouchmaking.

In such cases it is to be noted that the invention does not require, inmany respects, the use of any particular resin for the variouscomponents. This permits the use of backing substrates of e.g.polypropylene, polyester and nylon for desired barrier qualities thatpolyethylene does not provide.

Also, in cases desired, a wide range of compatibility layers may beemployed. For instance, for joining a polyester backing of a closurestrip to a polyester sheet or film, a lower melting point layer oneither component that adheres to each can be applied. In another case,or where the sheet is a plain or coated paper either a bonding layer maybe introduced to one f the mating surfaces or the substance of thebacking substrate itself may be used as the bonding surface, e.g. wherethe backing is polyethylene.

According to still another aspect of the invention, a reclosableflexible package is formed of flexible plastic film of wall thicknessless than about 0.005 inch and includes a reclosable, elongated closurein which the reclosable fastener has opposable strips adapted to befacially engaged to close the package. The strips are constructed to beusefully engaged upon application of a uniform facial engagement forceof less than about one pound per lineal inch of closure, and to beopened by a transverse peel force of less than about two pounds perlineal inch of closure.

In some embodiments each of the strips have a bi-dimensional field of atleast one type of discrete fastener elements, the fastener elements ofeach strip being constructed to individually interact with elements ofthe other opposable strip to form a field of localized releasablefastenings to form a peel-open closure. In some instances each strip hasat least two types of discrete fastener elements, with hooks of eachstrip engage with loops of the other.

In some cases the strips each comprise loops and loop-engageablefastener elements.

Preferably, the closure is less than about one inch in width and hasmultiple interlaced rows of loop-engageable fastener elements and rowsof loops. For instance, in some cases there are at least 10 rows ofloop-engageable elements and 10 rows of loops across the width of theclosure strip. Preferably, the fastener element density is greater thanabout 1000 fastener elements per square inch of closure.

In some cases the loops are formed of the filaments of multi-filamentyarn.

In some embodiments the closure contains a molded strip having parallelrows of fastener elements molded integrally with a face of the strip,and, interspersed between groups of from one to three adjacent rows offastener elements, at least one continuous, multi-filament yarn bondedthe face of the strip, with filaments of the yarn extending from theface of the strip for engagement by the fastener elements. Themulti-filament yarns may be permanently crimped or staked to the face ofthe strip at spaced apart points along the strip, for example.

In some instances the yarns are comprised of polyester.

In some cases the fastener elements are formed of polypropylene. Anotheraspect of the invention features a bag closure having matable touchfastener elements arranged in parallel strips extending from one surfaceof a bag. Between the strips of fastener elements is a frangible regionadapted to be torn apart to initially open the bag. After initialopening, the bag is reclosed by folding the closure about the tornfrangible region to engage the strips of matable fastener elements.

Various aspects of the invention can provide a bag closure that isreadily opened without the level of fine motor control required tomanipulate very small features. This can be particularly important forusers who, due to arthritis, weak eyesight or other disabilities have alower level of dexterity.

As a repeated use closure, the product of the invention can provide aventilated, easily alignable seal. As the bands of loops and fastenerelements may be made relatively wide, there is no need for accuratealignment to form a reliable closure. The closure is able to accommodatea fair amount of dirt or debris without losing its function as aclosure, making it particularly applicable as a closure for bagscontaining granular or powder substances. In addition, the naturalporosity of the closure can provide some degree of filtering of airbornedust. Such a ventilated closure can be particularly desirable in cargocontainers of airplanes in order to accommodate pressure changes, and,by its venting action, may help to avoid moisture buildup to keepproduce and other such items fresh. The continuous closure strip isreadily adaptable to standard bag-making equipment and, in manyinstances, is directly weldable to compatible bag materials. Theseadvantages accrue to bags produced according to the invention and havingsuch a repeated use closure.

If made of an appropriate width, the closure strip of the invention canbe folded and sealed to itself to form an enclosed bag.

Other features and advantages will be apparent from the followingdetailed description and attached drawings, and from the disclosures ofour earlier U.S. patents and patent applications incorporated byreference above.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a composite touch fastener in the formof a closure strip.

FIGS. 1A and 1H are enlarged views of areas 1A and 1H, respectively, inFIG. 1.

FIGS. 1B through 1G illustrate the structure of area 1A in various otherclosure strip embodiments.

FIG. 2A illustrates the application of fill-shifting loads in a baghaving the closure strip of FIGS. 1 and 1B.

FIG. 2B illustrates the application of peel force to the closure stripof FIGS. 1 and 1B.

FIG. 2C illustrates another closure strip configuration providing aninner/outer peel preference.

FIG. 3 is a cross-sectional view of the closure strip, folded andinstalled at the opening of a bag in a sealed condition.

FIGS. 4A and 4B illustrate a bag with the closure strip of FIG. 1, insealed and opened conditions, respectively.

FIG. 5 is an enlarged cross-sectional view of the outer edge of theclosure strip being grasped to open the bag.

FIG. 6 is a perspective view of a closure strip having a paper backing.

FIG. 7 illustrates a first method and apparatus for forming compositetouch fastener tapes, such as the closure strips of FIGS. 1 and 6.

FIG. 8 is an enlarged, unscaled view of the forming nip of the apparatusof FIG. 7.

FIG. 9 is a highly enlarged view of the loop material securing region ofthe nip of FIG. 8.

FIG. 9A illustrates an alternative arrangement of the loop materialstaking region.

FIG. 10 is an enlarged view of a portion of the outer edge of a stakingring.

FIG. 11 illustrates a second method and apparatus for forming compositetouch fastener tapes, such as the closure strips of FIGS. 1 and 6.

FIG. 12 shows a nip formed between a mold roll and a contoured pressureroll.

FIG. 13 is a transverse cross-section of a composite fastener tapeformed in the nip of FIG. 13.

FIG. 14 illustrates a first vertical form/fill bag-making apparatus.

FIG. 15 illustrates a second vertical form/fill bagging apparatus,configured to accommodate the closure strip of the invention.

FIG. 15A is an enlarged view of the means for joining the closure stripto the bag web in FIG. 15, with portions removed to show theconfiguration of the insulator rail and sealing jaws.

FIG. 16 is a cross-sectional view, taken along line 16—16 in FIG. 15.

FIG. 16A is a cross-sectional view, corresponding to FIG. 16, with aninverted closure strip arrangement.

FIG. 17 shows a first inverted horizontal form/fill packaging apparatusand method, with the closure strip fed into the fin seal between the webflanges.

FIG. 17A is a cross-sectional view, taken along line 17A—17A of FIG. 17.

FIG. 18 shows a second inverted horizontal form/fill packagingconfiguration, with the closure strip wrapped about the web flanges.

FIG. 18A is a cross-sectional view, taken along line 18A—18A of FIG. 18.

FIG. 19 shows a third horizontal form/fill packaging method, with thefin seal formed on the underside of the packages.

FIG. 20 shows an apparatus and method for forming bags to be filled froman open end opposite their closures.

FIG. 21 is a cross-sectional view, taken along line 21—21 in FIG. 20.

FIG. 22 is an enlarged view of area 22 in FIG. 20, showing theconfiguration of the closure as applied to the web.

FIG. 23 shows one configuration of an edge seal formed between twoadjacent bags in the process of FIG. 20, for forming exposed closurepull tabs.

FIG. 24 illustrates opening a bag with an exposed closure pull tab, suchas formed from the edge seal configuration of FIG. 23.

FIG. 25 shows another method for forming pouches, in which the closurestrip is bonded to the edges of a sheet of bag film as the film isfolded.

FIG. 26 illustrates making reclosable bags from two parallel plasticwebs and a closure strip.

FIG. 26A shows a bag made by the process of FIG. 26.

FIG. 27 shows a package having a broad closure strip displaying consumerinformation.

FIG. 28 is a transverse cross-section through the closure strip includedin the package of FIG. 27.

FIGS. 29 and 30 are enlarged views of areas 29 and 30, respectively, inFIG. 28.

FIG. 31 is a cross-section through a bag having a closure strip withexposed loop-engageable elements extending from an outer bag surface.

FIG. 32 illustrates a method and apparatus for forming the closure stripof FIG. 31.

FIG. 33 is a partial outer view of an upper corner of a pouch having arecloseable top.

FIG. 34A is a side cross-sectional view of the pouch of FIG. 33, takenalong line 34A, showing the structure and attachment of the closurestrip.

FIGS. 34B and 34C sequentially illustrate the opening and reclosing ofthe pouch of FIG. 34A.

FIG. 35A is a cross-sectional view through the closure end of a roll-topbag.

FIGS. 35B through 35D sequentially illustrate the opening and reclosingof the bag of FIG. 35A.

FIG. 36 is a cross-sectional view through the closure end of a bag withan inverted closure.

FIG. 37 illustrates a method and device for attaching the closure stripto the bag of FIG. 36.

FIGS. 38A–38C show rolled bag films with pre-applied closures, invarious configurations.

FIG. 39 is a perspective view of a reclosable bag.

FIG. 40 illustrates the bag of FIG. 39 being opened by pinching andpulling.

FIG. 41A is a cross-sectional view of the closure end of the bag, takenalong line 41A—41A in FIG. 39.

FIG. 41B shows the bag cross-section of FIG. 41A with the bag initiallyopened and then folded about the opening to engage the fastener elementsof the closure.

FIG. 42 illustrates the closure, in transverse cross-sectional view,before being attached to bag material.

FIG. 43 is an enlarged view of area 43 in FIG. 42.

FIG. 44 is a cross-sectional view, taken along line 44—44 in FIG. 43.

FIG. 45 is a cross-sectional view similar to FIG. 41A but of a baghaving an edge pull tab along the lower closure edge.

FIG. 46 is a perspective view of another bag, having a front face pulltab.

FIG. 47 shows a bag having a closure tear rib with a graspable end.

FIG. 48 illustrates a third vertical form/fill bagging apparatus andmethod, in which the closure strip is applied to the bag film before thefilm is wrapped about the forming head.

FIG. 49A is a cross-sectional view, taken along line 49A—49A in FIG. 48.

FIG. 49B is taken from the same perspective as FIG. 49A, with adifferent closure strip configuration.

FIGS. 50A and 50B show closure strips with peelable seals.

FIG. 51 shows a hook-to-hook engagement between facing bands ofoppositely-directed, hook-shaped fastener elements.

FIG. 52 is a cross-sectional view, taken along line 52—52 in FIG. 51.

DETAILED DESCRIPTION

Referring to FIG. 1, a lengthwise-continuous closure strip 100, such asfor sealing a bag, consists of a thin, sheet-form resin substrate 102with lengthwise-continuous, parallel bands 104 and 106 of loops andfastener elements, respectively, on its front face 108. Bands 104 and106 are equally spaced from the center “C” of the closure strip, suchthat when the strip is folded longitudinally at “C” to cover front face108, the fastener elements of band 106 engage and retain the loops ofband 104 to form a releasable fastening. The fastener elements 110 ofband 106 are integrally molded with and extend from front face 108. Inthis embodiment, these fastener elements are in the form of J-hooks thatextend, in rows, along the length of the closure strip. Some of theJ-hooks face in opposite directions along the strip. Other fastenerelement shapes may also be employed, including those that overhang thesubstrate 102 in a widthwise direction. A suitable fastener elementshape is the CFM29 hook shape (of about 0.015 inch in height), availablein various products sold by Velcro USA in Manchester, N.H.

Band 104 of loops consists of a preformed, non-woven web of polymerfibers, which may include a stabilizing binder, and which are bonded tofront face 108 of substrate 102 at various points across the width andlength of the web. Suitable loop materials include those disclosed inU.S. Pat. No. 6,342,285, and in the related PCT patent applicationPCT/US98/18401, filed as a continuation in part of the foregoingapplication, the entire disclosures of which are hereby incorporated byreference as if fully set forth.

Preferably, the non-woven loop material in band 104 is very thin, suchas less than about 0.040 inch thick (more preferably, less than about0.020 inch thick), with web fibers held in a transversely stretchedcondition and freestanding loop structures extending from its exposedsurface. As discussed in the above-referenced patent applications, theloop structures extend from associated knots in the stretched web, whichmay be stabilized by liquid binder wicked into the knots and cured.Between knots, the thin fiber mat is not very dense and is sheer enoughto permit images to be readily seen through it. Overall, the loopmaterial has a basis weight (in its preformed state, including anypre-applied binder) of less than about 4 ounces per square yard (136grams per square meter), preferably less than about 2 ounces per squareyard (68 grams per square meter). Other details of this loop materialmay be found in the above-referenced applications. For applications inwhich the loop material is partially penetrated by resin of thesubstrate as the substrate is formed (as discussed below), the needledloop material is preferably only stretched in a transverse directiononly about 22 percent to leave a fair amount of loft and avoid totalpenetration.

In some instances, loop material 104 is partially encapsulated directlyin resin of the substrate as the substrate is formed in a continuousmolding process (described below). In other cases, it is bonded to theformed substrate, either by ultrasonic bonding, welding, or adhesives.

Some lightweight knits are also suitable loop materials for certainapplications. Examples of such knits are Product 19902 from GuilfordKnits in Greenville, S.C., which is of polyester fibers and has a basisweight of only about 1.6 ounces per square yard. For a heavier knit, weprefer Guilford's Product 19029, a nylon knit of about 3.3 ounces persquare yard. Lightweight knit products are also available from TYBOR inSpain, and MIZARD in Italy.

FIGS. 1A through 1D illustrate various patterns of variable bondingbetween loop material 104 and substrate 102. Such variable bondingpatterns correspond, in some cases, to variable resin penetration intothe web of the loop material, which may be achieved by employingdifferent arrangements of staking rings and/or barrier materials betweenthe loop material and substrate, both of which are discussed furtherbelow. In FIG. 1 a, loop material 104 is only fully penetrated bysubstrate resin in narrow edge regions 114, and is less penetrated atits center. For instance, if loop material is about ¾ inch wide (W_(L)),then fully penetrated edge regions 114 may have a width of only about ⅛inch (w_(e)). The center region of the loop material is less penetratedand gently arches away from the substrate, presenting the loops forengagement. The inclined sides of the center arch can also help toenhance the peel strength of the fastening at the edges of the loopmaterial, as they resolve a small component of the peel force in atangential, or shear, direction.

In FIG. 1B, the loop material is fully bonded to the substrate in narrowbands 116 spaced inward from its edges, leaving edge regions 118relatively lightly bonded, or even loose. One advantage of this bondingpattern is that the inner edge region 118 on the inside of theassociated bag helps to deflect separation loads caused by shifting bagcontents, which would otherwise generate high peel forces between thefastener elements and the loops, into separation forces between the loopmaterial and substrate (as illustrated in FIG. 2A). The high bondingstrength of inner band 118 helps to avoid delamination of the loopmaterial from the substrate. Another advantage of this bonding patternis that it enhances initial peel strength of the fastening, as the outeredge region 118 of the loop material follows the fastener elementsduring peel until it is separated in shear (FIG. 2B).

Having only one inner edge region 118 unbonded can in some instancesprovide better inner opening resistance (e.g., from content shifting)than having both inner edge regions free. We presently prefer to leaveonly the edge of the loop side of the closure strip unattached to thebag web in most cases, as shown in FIG. 31 (discussed below), with thehook side edge bonded to the inner surface of the bag web.

Another closure arrangement for providing good resistance to beingopened from inside the bag but readily opened from outside the bag isshown in FIG. 2C. All of the hook elements 250 are arranged with theirloop-engaging tips facing the inside of the bag, providing a differencein inside and outside peel resistances. With the hooks fully engagingthe loops of loop material 252, peel forces applied to the closure bymovement of bag contents in the direction of arrow “A” are resisted to agreater degree than user-applied peel forces in the direction of arrow“B”.

The pattern of variable bonding shown in FIG. 1C creates transversepillows 120 of relatively lightly bonded, or loose, loop materialseparated by transverse bands 122 of relatively more fully bonded (e.g.,more deeply encapsulated) loop material. The loftiness of pillows 120 isexaggerated for illustration. This pattern provides some of thepeel-enhancing and load-shifting advantages of the pattern of FIG. 1B,due to the “free” pillow ends along the inner and outer edges of theloop material.

FIG. 1D illustrates a bonding pattern with longitudinal pillows 124 ofrelatively lightly bonded, or loose, loop material, separated bylongitudinal bands 126 of relatively more fully bonded (e.g., moredeeply encapsulated) loop material. Again, the loftiness of the pillowsis exaggerated for illustration. FIG. 1E is a variation of the patternof FIG. 1D, with each longitudinal band of more fully bonded materialseparated into longitudinally alternating regions of light and heavybonding. The regions of light and heavy bonding are staggered across theloop material, producing a checkerboard pattern of lofted loop pillows.In the pattern illustrated in FIG. 1F, the center region of loopmaterial 104 is heavily bonded to the substrate about the peripheries ofspaced apart, circular lofted regions 125 which are less firmly bonded.The exposed surfaces of the lofted loop pillows 125 extend outward topresent loops for engagement. Other shapes of lofted regions 125, suchas ovals, may also be employed. One of the edge regions of the loopmaterial of FIG. 1F is similar to the edge regions shown in FIG. 1B,while the other forms transverse pillows similar to those of FIG. 1C.FIG. 1G shows a bonding pattern with edge regions 128 of alternatinglight and heavy bonding, and a center region bonded in only isolatedregions 130. The bonding patterns described above may be mixed andvaried for different applications, as required.

As an alternative to feeding a preformed sheet of loop material into aforming nip to create the loop band 104 of the closure strip, engageableloops may be formed subsequent to forming the base of the closure stripby stitching loops directly into the base (as in a MALAMO process), orby bonding a strip of loop material to the face of the closure strip.

Referring back to FIG. 1, molded into the front face 108 of substrate102 along its center is a hump-shaped longitudinal rib 132 between apair of grooves 134 molded into front face 108.

As shown in FIG. 1H, one example of this rib 132 has a height of about1/32 inch and a width of about 1/32 inch at its base. The rib may have ahump-shaped profile, as shown, or a rectangular cross-section withparallel sides. The rib is preferably longitudinally continuous, asshown, but may alternatively be formed as a row of appropriately shapedprotrusions. At least one of the flat regions 135 between grooves 134and the loop and hook bands 104 and 106 in FIG. 1 contains, in somecases, a layer of adhesive such as a pressure sensitive adhesive (notshown), for providing a reclosable seal for applications where aresealable opening is desired. In these instances surfaces 135 providean airtight, non-ventilated seal when the bag is closed, and supplementthe mechanical closure strength of the hook and loop fasteners.Preferably, an adhesive is employed which has been compounded so that itsticks primarily only to itself or to the opposing face of thesubstrate, so as to not pick up excessive debris from the bag contents.In other, non-illustrated embodiments, either grooves 134 or rib 132, orboth, are formed on the back face of the substrate, opposite thefastener elements and loop material.

The formed closure strip 100 is permanently installed at the openableend of a bag by attaching edge regions 136 of the closure strip to outeredges of the bag at its opening, with the loop and hook bands facingeach other, as shown in FIG. 3. The bag may be attached to the back faceof the closure strip as shown, in which case edge regions 136 aredefined on the back face of the closure strip, or on the front face,with the edges of the bag on the inside. Methods of attaching theclosure strip to the bag include, but are not limited to, welding,gluing, adhering or stitching. One preferable method of attaching aclosure strip to a bag of a compatible resin is by directly welding theresin of the closure substrate to the resin of the bag, as discussedbelow. In this manner, polyethylene closure strips may be readily weldedto polyethylene bags.

FIG. 4A illustrates a sealed bag 138 having a polyethylene body 140welded to closure strip 100 across its openable end. Preferably, thethickness of the substrate of the closure strip is about the same as thethickness of the material of the bag body, in the range of 0.002 to0.005 inch. Substrates of up to at least 0.015 inch in thickness,however, may be produced by the methods described below. To initiallybreak the seal and open the bag, the outer fold of closure strip 100 isgrasped and pulled, thereby tearing the folded edge from the bag fromone end of the bag to the other, as shown in FIG. 4B. In grasping theouter fold of the closure strip, the middle rib 132 is grasped betweenthe thumb and forefinger. Rib 132 thus provides an edge of increasedthickness for easy grasping. As the folded edge of the closure strip istorn away, the closure strip tears along grooves 134. Grooves 134function as frangible tear points for initially opening the associatedbag, and may be straddled by an associated local thickening of thesubstrate, such as in the form of ribs or rows of raised bumps (notshown) to direct the propagation of the tear along the grooves.

Preferably, the resin of the substrate of the closure strip iscompatible with the resin of the bag body, to enable direct welding ofthe two together. In situations where this is not practical, a separatelayer of a bag-compatible material may be provided on the closure strip.For example, a layer of paper 142 may be bonded to either the front faceof the closure strip (e.g., in edge regions 136 in FIG. 1), or acrossthe back face of the closure strip as shown in FIG. 6, or along just theedges of the back face of the closure strip (not shown). The paper 142may be directly bonded to the resin of the substrate (e.g., during theforming of the substrate, as described below), or joined with adhesiveafter the substrate is formed.

FIG. 7 illustrates one method and apparatus for producing theabove-described closure strips. The method builds upon the continuousextrusion/roll-forming method for molding fastener elements on anintegral, sheet-form base described by Fischer in U.S. Pat. No.4,794,028, and the nip lamination process described by Kennedy, et al.in U.S. Pat. No. 5,260,015, the details of both of which areincorporated herein by reference. The relative position and size of therolls and other components is not to scale. An extrusion head 150supplies a continuous sheet of molten resin to a nip 152 between arotating mold roll 154 and a counter-rotating pressure roll 156. Moldroll 154 contains an array of miniature, fastener element-shaped moldcavities extending inward from its periphery (not shown) for molding thefastener elements. Pressure in nip 152 forces resin into the fastenerelement cavities and forms the substrate. The formed product is cooledon the mold roll until the solidified fastener elements (e.g., hooks)are stripped from their fixed cavities by a stripper roll 158. Alongwith the molten resin, a continuous strip of loop material 160 (whichbecomes loop band 104 in FIG. 1) is fed into nip 152, where it ispartially impregnated by resin and becomes permanently bonded to thefront face of the substrate. Thus the product 162 that is stripped fromthe mold roll includes both fastener elements and loops.

For higher production rates, two or more widths of closure strip may besimultaneously produced on a single mold roll, and later split andspooled. Referring also to FIG. 8, two strips 160 of loop product arefed in parallel into positions 164 along nip 152. Molten resin isintroduced across the entire nip, forming two bands of hooks in regions166. Mold roll plates of appropriate widths and edge configurations arearranged to produce the ribs and grooves at the center of each closurestrip. A splitting channel ring 168 at the center of the mold rollproduces a splitting channel in the product, along which the resultingtape is split by a blade 170 (FIG. 7; either stationary or rotating)into two separate runs of closure strip which are separately spooled. Insome configurations, a wide section of the mold roll surface is definedby a single, solid roll sleeve having a profiled outer surface forforming one or more of the series of features extending along theclosure strip. For instance, in one arrangement, the entire width W_(A)of the mold roll surface between the hook bands is defined by a singlesleeve having a ground circumferential profile defining all featuresbetween the hook bands. When thin staking rings (discussed below) areemployed in the loop material regions 366, widths W_(B) and W_(C) of themold roll surface are preferably formed by solid, wide mold rollsections. Employing such wide plates provides additional resistance tomold roll bending loads caused by molding nip pressures, enabling widerproduct widths to be formed without excessive product thicknessvariations.

FIG. 7 also indicates several variations of the above-described method.For instance, rather than introduce the loop material 160 through nip152 and thereby join it to the substrate as the substrate is molded, theloop material may be joined to the substrate after the substrate hasbeen formed, such as is indicated by the run 160′ of loop material shownin dashed outline. In this case, front face idler 172 is heated and hasa contoured surface for producing the desired pattern of bonding betweenthe loop material and the substrate. Paper may be joined to the backface of the substrate, to produce the product shown in FIG. 6, by eitherrunning a strip 174 of paper through nip 152 on the pressure roll sideof the resin, or by adhering adhesive-coated paper 174′ to the formedsubstrate either at stripping roll 158 or at idler 176. In some cases,adhesive-coated paper 174′ includes a transfer coating, such that itspaper backing may be peeled from the adhesive on the back of the productto secure the back of the final product to a supporting surface. Theadhesive applied to the back of the product in this manner may be eithera pressure-sensitive or heat-activated adhesive, for instance. Fordecreasing the permeability of the final product, a second flow of resin(either molten or in the form of a film) may be added to the nip againstpressure roll 156, as strip 174 is shown, to form a backing on the finalproduct. For instance, a layer of polyester may be added to reduce thepermeability of a polyethylene closure strip, such as for packagingcertain foods. Adding a strip of barrier material 178 between the loopmaterial and the molten resin optionally controls the pattern ofpenetration of resin into the loop material in nip 152. Barrier material178 is, in some instances, a perforated paper or film that allows resinto pass into the loop material in selected regions but inhibits its flowinto other regions, such as for producing the bonding pattern of thecenter region of loop material shown in FIG. 1G. The barrier materialmay also be a homogeneous sheet of material having a high porosity,equally limiting the penetration of resin into the loop material acrossthe width of the barrier material. Rather than be introduced as aseparate sheet, in some cases the barrier material is pre-applied to thesurface of loop material 160 and may be in the form of a binder locatedin discrete areas of the loop material and locally encapsulating fibersof the loop material, for instance. In many cases, the barrier materialis narrower than the loop material, and centered along the width of theloop material, to enable full penetration of resin into the edges of theloop material. In some cases, however, as to produce the bonding patternof FIG. 1B, for instance, thin strips of barrier material are run intothe nip along the edges of the loop material to inhibit the bonding ofedge regions 118 (FIG. 1B) to the substrate. Other arrangements ofbarrier and loop materials, and resulting bonding patterns, will beapparent upon reading this disclosure. In all cases in which the barriermaterial becomes permanently bonded to the substrate and thereforebecomes an integral part of the final product, it should be selected forits low material cost and weight.

FIG. 9 illustrates the bonding of the loop material 160 to the resin ofthe substrate in area 164 of nip 152 (FIG. 8). “Staking” rings 180 oneither side of a reduced diameter plate 182 engage the edges of the loopmaterial to locally hold the edges of the loop material against theresin of the substrate as the resin forms the substrate under nippressure, thereby ensuring heavy penetration of the loop material inpredetermined areas along its edges. This configuration shown in FIG. 9produces the bonding pattern illustrated in FIG. 1A, the staking rings180 forming heavily bonded edge regions 114, the width we correspondingto the width of the staking ring. The staking rings may extend slightlybeyond the nominal mold roll diameter, as shown in FIG. 9, or be flushwith adjoining mold roll rings (as shown in FIG. 9A, for example).

To form a row of heavily bonded points separated by regions of lowerresin penetration, some staking rings 180 have a contoured outer edge asshown in FIG. 10. A series of protrusions 184 extending beyond thenominal diameter D_(s) of the staking ring cause the resin to locallypenetrate farther into the loop material. In this example configuration,D_(s) is 9.968 inches, the height (h_(s)) of each protrusion 184 is0.014 inch, and the inner and outer radii (R) at the flank of eachprotrusion is 0.015 inch. The protrusion pitch (P_(s)) is 0.190 inch,and the length of the flat between protrusions (W_(f)) is 0.130 inch.The dimensions of the protrusions are selected to attempt to optimizethe maximum approach angle α_(f) of the protrusion flank with respect toa local ring tangent. A steep approach angle (i.e., an abrupt change inring diameter) can cause a sharp local increase in nip pressure and anundesirable local flooding of the front side of the loop material withresin. Such flooded areas can create local “depth stops” to matingfastener elements, reducing the fastener element penetration into theloop material. A zero approach angle (i.e., no protrusions) would resultin a homogeneous resin penetration beneath the staking ring, which maynot be as desirable as local loop material “pillowing” (discussed above)in some applications. The maximum approach angle α_(f) in theillustrated staking ring embodiment is about 40 degrees. A shallowerangle (e.g., of about 30 degrees) may be preferable in some cases, asmay a longer spacing w_(f) between protrusions to provide longer, loftedpillow regions.

FIG. 9A shows a staking ring configuration for producing the bondingpattern shown in FIG. 1E. Staking rings 186 having the profile shown inFIG. 10 are stacked together with staggered protrusions, such that thepattern of heavily bonded regions resembles a checkerboard withelongated “pillows” extending outward between the heavily bondedregions. The width w_(s) of each ring is about 0.018 inch.

This in situ staking method for attaching loop material to the resin ofa fastener substrate as the substrate is being formed has broadapplicability to the production of composite touch fasteners. Forexample, FIG. 12 shows a nip 152′ between a mold roll 154′ and apressure roll 156′. Mold roll 154′ contains many thin fastener elementmolding rings 214, which may be alternated with spacer rings (notshown), to integrally mold fastener elements extending from one side ofa sheet-form base as taught by Fischer. In this case, however, pressureroll 156′ has a pattern of protrusions 216 extending from its otherwisesmooth surface. The protrusions locally narrow gap 152′ in discreteregions, causing a variation in nip pressure during formation of thefastener tape. Running a fibrous preformed material through the nipagainst the pressure roll with the molten resin, as taught by Kennedy,et al., will, in this configuration, cause fibers of the preformedmaterial to be encapsulated more fully in the resin in areascorresponding to protrusions 216. This in situ “staking” method isparticularly useful when the fibrous preformed material is a veryporous, thin material such as a needled non-woven web with a low basisweight. The pattern of protrusions on the pressure roll is selected toform an inverse pattern of lofted “pillows” of loop material at mostonly partially encapsulated in the substrate resin.

FIG. 13 is a transverse cross-section of a composite fastener tape 218produced in this fashion, having an array of hook-shaped fastenerelements 220 extending from one side of the substrate 222, and alightweight, non-woven web of loop material 224 permanently bonded to anopposite side of the substrate. Loop material 224 is coextensive withthe substrate in this case (i.e., it extends across the full width ofthe substrate), but is fully encapsulated in substrate resin only indiscrete regions 226. Between regions 226, the loop material forms theabove-described “pillows” 228, or lofted regions, which are not fullyencapsulated in resin. The loft of pillows 228 enables the heads offastener elements 220 to penetrate the loop material and engageindividual fibers during fastening. A similarly contoured pressure roll156′ (FIG. 12) may also be employed to attach a strip of loop materialto the fastener element side of a fastener tape.

FIG. 11 illustrates an alternative method and apparatus for forming theabove-described closure strips. The contoured surface of an extrusionhead 188 (sometimes called an injection head) is placed adjacent a moldroll 154 (with fixed fastener element molding cavities as describedabove with respect to FIG. 7), and a continuous flow of molten resin isinjected under pressure into the gap 190 defined between head 188 andmold roll 154, filling the fastener element cavities and forming thefront and back faces of the substrate. The configuration andconstruction of mold roll 154 is the same as is shown in FIG. 8, inwhich member 156 may be taken to be the adjoining extrusion head. Thestrip 160 of loop material is fed through a predetermined region of gap190, and held up against the surface of mold roll 154 by resin pressurein the gap. In this manner, the loop material is partially impregnatedwith substrate resin and permanently bonded to the front face of thesubstrate. In applications where it is not possible to fill the fastenerelement cavities without completely saturating the loop surface of theloop material with resin, a strip of barrier material 178 may be fedthrough gap 190 between head 188 and loop material 160. Barrier material178 is discussed in more detail above with respect to FIG. 7. For someapplications a strip 174 of paper or other suitable backing material islaminated to the back face of the substrate while the molded product isretained on mold roll 154, by pressure supplied by a pressure roll 192,as shown in dashed outline. Alternatively, a strip of adhesive-coatedpaper 174′ may be adhered to the formed substrate either at strippingroll 158 or at idler 176.

FIG. 14 illustrates an inverted vertical form/fill (VFF) method andapparatus for forming and filling bags (such as bag 138 of FIG. 4A).Closure strip 100 and a sheet of bag material 194 are each folded andfed about a longitudinal mandrel 196, with their edges overlapping attwo points. In the embodiment shown, both the bag material 194 and thesubstrate of closure strip 100 are polyethylene. Two heated rollers 198(only one visible from the perspective illustrated) weld the edges ofthe closure strip and bag material together to form a continuous tube200 with two longitudinal sealed seams. In the apparatus shown, tube 200extends upward through a lower sealing/cutting device 202 and an uppersealing device 204. In the bag forming and filling sequence, tube 200 isadvanced upward until its open end is aligned with upper sealing device204. Lower sealing/cutting device 202 then forms a transverse sealacross the tube to form one sealed side of the resulting bag. The bag isthen filled from above, through the still open end of the tube, withmaterial supplied through chute 206. After a predetermined amount ofmaterial has been released into the bag, the open end of the tube issealed by upper sealing device 204 to form a sealed bag 138, which isthen severed from tube 200 by cutting the tube just below the previouslyformed transverse seal by lower sealing/cutting device 202. Theresulting bag 138 has one edge 208 of folded bag material 194, twosealed edges 210, and one edge 212 of folded closure strip 100. Othermethods of sealing closure strips to bag materials are known to those ofnormal skill in the art of bag making. For instance, for sealing thepaper-covered surface of closure strip 100′ (FIG. 6) to a paper bagmaterial 194, a layer of adhesive would normally be applied between theoverlapping paper edges of the closure strip and bag material.

FIG. 15 illustrates a modification to a more common VFF machineconfiguration, for continuously securing the above-described closurestrip to a flow of bag-forming web during the forming and filling ofindividual bags. The bag-forming web consists of a thin sheet ofthermoplastic film 254 which is shaped into a tube by being fed over afilling tube 256, which has an upper funnel end 258 through whichcontents are discharged to fall into individual bags formed of the film.Film 254 is fed from a roll (not shown) over an attitude roller 260, andguided onto the fill tube by curved guide forms 262. In some cases, thefilm is advanced continuously and the transverse sealing jaws 264(described below) reciprocate vertically, traveling with the film duringthe sealing/cutting process (as indicated by arrows 265); in other casesthe film is advanced incrementally and the transverse jaws remain withinthe same horizontal plane.

As film 254 is formed into a tube, its two longitudinal edges 268 formflanges extending generally radially from the tube, between which acontinuous length of closure strip 266 is fed in a folded condition,such that the edge regions of the web film lie at least partiallyagainst the outer sides of the closure strip in face-to-face relation,but do not overlap the folded edge of the closure strip. Guide rollers270 above the closure sealing bars 272 maintain the adjacency of thesides of the closure strip and the film edges. Closure strip 266 is fedover a contoured insulating rail 274 extending longitudinally along thefill tube from above guide rollers 270 to below closure sealing bars272. As shown in FIGS. 15A and 16, insulating rail 274 has alongitudinal groove along each of its sides. One groove accommodates theloop material 104 so as to avoid crushing the extended engageable loops,and the other groove receives the hooks 106 of the closure strip,helping to guide the closure strip through the sealing process. Rail 274also has a notch extending along its distal end, for accommodating themiddle grasp rib 132 of the closure strip. The primary purpose ofinsulating rail 274 is to inhibit undesired welding of the inner sidesof the closure strip together as the edges of the bag film are welded tothe outer surfaces of the closure strip by closure sealing bars 272 (seeFIG. 16). When not employing an insulating rail, the closure strip maybe configured to utilize the insulating properties of the loop materialto avoid permanent welding together of the inner surfaces of the closurestrip, as discussed more fully below.

Closure strip 266 may either be spooled from roll 276 over guide roll278 in a folded condition, as shown, with its hooks and loops engagedand then pulled over insulating rail 274, thus separating the hook andloop sections of the closure strip, or the closure strip may be spooledflat and then folded about the insulating rail, thereby avoiding havingto disengage the hook and loop sections in the process.

Closure sealing jaws 272 each have a longitudinal groove adjacent thelongitudinal grooves of insulating rail 274, such that the heatedsealing jaws slidingly contact the film edge regions only on either sideof the hook and loop bands of the closure strip, sealing the film to theclosure strip in two discrete bands on each side of the closure strip.Sealing jaws 272 have appropriate heating elements embedded within them(not shown) to maintain the sealing surfaces at a predetermined,elevated temperature. To leave the inner edge of the loop side of theclosure strip free from the film to form an anti-peel flap (as discussedabove with respect to FIGS. 2A and 2B), the sealing jaw 272 on the loopside of the closure is at least partially recessed, as shown, to avoidbonding the inner edge of the loop side of the closure strip to the bagfilm. To form an even wider anti-peel flap, the sealing jaw 272 on theloop side of the closure may be configured to contact the bag film onlyoutboard of the band of loop material 104.

Immediately below the lower edges of sealing jaws 272, insulating rail274 terminates and the hook and loop bands of the closure strip arepressed together between a pair of rollers 280, just above the lower endof fill tube 256.

After a selected amount of contents have discharged through the lowerend of the fill tube, transverse sealing jaws 264 come together aboutthe bag film and closure strip and form two parallel, transverse seals284, each of which will form the sealed edge of a bag. As jaws 264travel with the advancing film, a cutting knife 282 within the jawssevers the film and closure strip between the transverse seals 284. Whenjaws 264 open at the end of the sealing cycle, a fully formed, filledand severed bag 286 is complete.

FIG. 16A shows another configuration of sealing a closure strip 288 toedge regions of a film web 254 as the film web is fed about a fill tube256, for creating what we call an inverted closure having free outeredges and a recessed center portion. In this configuration the closurestrip is guided over a separate insulating rail 290 that extends betweenthe film edges and the opposing sides of the closure strip, similar incross-section to the insulating rail of FIG. 16 but in oppositeorientation. In this case closure strip 288 is provided with a centertear notch 292, rather than a center rib, along which the closure isburst to initially open the bag. In the bag formed with this styleclosure, the hook and loop elements are not exposed to the bag contentsprior to the initial opening, and the center portion of the closurestrip provides a tamper-evident seal. Closure strip 288 is permanentlysealed to the bag film by heated sealing jaws 272′ which are similar inconstruction to sealing jaws 272 of FIG. 16.

FIGS. 17–19 illustrate three examples of horizontal form/fill (HFF)machines and processes featuring the above-described closure strips.Referring first to FIG. 17, a bag film 254 is continuously fed from roll294 over attitude roller 296 and into a forming head 298 shaped to formthe film into a rectangular tube 300. As with the VFF method describedabove, the edges of the film are brought together to form aperpendicular fin 302 extending from one side of the tube. In this case,closure strip 100 is fed from roll 304, folded to engage the hook andloop bands, passed about angled roller 306, and fed into the nip betweenheated fin seal rollers 308 between the edges of the bag film. Meanwhileindividual products 310 to be packaged (e.g., trays of cookies) are fedthrough the forming head and into film tube 300 at a predeterminedspacing and rate corresponding to the speed of the bag film.

As shown in FIG. 17A, the outer surfaces of folded closure strip 100 arepermanently welded to the extending film flanges forming theperpendicular fin 302 of the film tube in the nip between fin sealrollers 308. No insulating rail is needed between the inner surfaces ofthe closure strip in this case because the air between the hooks andloops extending from the inner surfaces of the closure strip preventsextensive welding inside the closure strip. With proper adjustment ofthe temperature and pressure of rollers 308, which depends on the typeof resin employed and the line speed, among other things, at most only asmall fraction of the heads of hook elements in hook band 106 will belightly bonded to either loop material 104 or the resin in which theloop material is embedded. This small amount of bonding willadvantageously increase the amount of peel force required to initiallyopen the package, leaving a sufficient proportion of undamaged hookelements to provide adequate engagement upon reclosure. We note thatwith many hook and loop resins, speeds, temperatures and pressures willhave to be carefully adjusted and controlled to provide a light bondwhile avoiding rapid progression of hook melting.

Referring back to FIG. 17, diagonal offset folding rollers (not shown)fold over the fin seal, and a pair of offset rollers 312 carrying aheated seal bar and cutting blade seal the ends of the bags and severthe bags from each other.

FIG. 18 shows a similar HFF process, in which the closure strip 100 isfolded over on the outside of both the bag film flanges and a fin sealinsulating rail 314 that extends to just downstream of heated finsealing rollers 308. Passed around angled roller 306, closure strip 100is folded within a guide channel 316 such that the edges of the closurestrip overlap the edges of the bag film, as shown in FIG. 18A. Theseoverlapped regions are welded together on either side of insulating rail314 by the fin sealing rollers, permanently bonding the closure strip tothe bag film. As the fin seal is folded over before passing betweenoffset rollers 312, the hook and loop bands of the closure strip arepressed together, before the inner surfaces of the bag film flanges arewelded together at the end seals of the bag. The hook and loop bands mayalso be welded together at the end seals, if desired, by providingsufficient heat, pressure and dwell time of the portion of the heatedsealing bar of the offset rollers that contacts the closure strip at thehook/loop interface.

FIG. 19 illustrates the incorporation of a reclosable closure strip intoa more common HFF machine configuration, with the longitudinal fin seal302 formed on the bottom side of the rectangular film tube 300. As inFIG. 18, closure strip 100 is folded about the outside of the extendedfilm edge flanges, which are separated by an insulating rail (not shown)that extends through the nip between the fin sealing rollers 308.

FIG. 20 shows another application of our closure strip in a bag-makingprocess. Closure strip 318 is differs from the closure strip shown inFIG. 1 only in that in contains a pull cord 320 (FIG. 22) embedded alongits central rib 132. The pull cord is configured to tear through theclosure strip and bag film longitudinally between the hook and loopbands when pulled transverse to the closure strip, and therefore must beof sufficient tensile strength to tear through the closure strip resinwithout breaking. Suitable pull cord materials include drawn nylons,such as fishing line, for example. The pull cord is embedded within theresin of the center closure strip rib by being continuously fed into therib-forming channel 322 of the mold roll (FIG. 8) prior to theintroduction of the rib-forming resin (such as long the feed pathlabeled 178 in FIGS. 7 or 11). Appropriate guides (not shown) arerecommended to keep the pull cord from walking out of the rib-formingchannel.

Closure strip 318 is passed around a guide roller 324 to travel with bagfilm 254 onto a folding collar 326 where it is permanently bonded to thefilm under heat and pressure by a sealing shoe 328. As shown in FIG. 21,sealing shoe 328 slidingly engages the closure strip along three bands,forming three continuous welds 330 between the closure strip and bagfilm 254. Collar 326 supports the bag film against the light pressureapplied by the sealing shoe. The channels 332 and 334 in the sealingshoe accommodate the hook band 106 and center rib 132 of the closurestrip, accordingly, and maintain the transverse location of the closurestrip during bonding. The outer edge of the loop side of the closurestrip is not welded to the bag film in this instance, to provide aninternal anti-peel flap in the finished bag, as shown in FIG. 22. Otherbonding configurations are employed for various applications.

Once welded together, bag film 254 and closure strip 318 are foldedalong their longitudinal centerline and passed between two drive rollers336 that press the hook and loop bands of the closure strip together andensure an appropriate crease along the spine of the closure strip. Thefolding of the bag film and closure strip is effected by collar 326 anda creasing idler 338 that runs along the center of the closure strip anddefines a rim groove 340 for receiving the center rib of the closurestrip during folding.

The folded bag film next passes between a pair of reciprocatingsealing/cutting jaws 342 which close against the outer surfaces of thebag film to seal the two sides of the folded bag film and the foldedclosure strip together to form a series of individual pouches, eachpouch sealed on three sides and having a single open end 344 forsubsequent filling. Jaws 342 may be configured to also sever the pouchesfrom each other during sealing, or to leave the pouches connected in theform of a string of pouches that is readily pulled through an adjacentfilling/closing station (not shown).

FIG. 23 gives one example of a pouch side seal configuration formed bythe jaws 342 of FIG. 20, in which a slot 346 and notch 348 are die-cutwithin the vertical seal formed between adjacent pouches. The heatedfaces of jaws 342 form complementary die parts for cutting through thebag film and closure strip to form the configuration shown as theinter-pouch seal is formed. The pouches are then filled through theiropen ends, which are subsequently sealed closed. By severing the lowersegments 350 joining adjacent pouches along centerlines 352, extendedpull tabs 354 are formed at the edges of each pouch. Each pull tab 354contains an end portion of pull cord 320, and provides convenient meansfor grasping and pulling the pull cord through the closure strip alongthe pouch, as shown in FIG. 24.

In the bag-forming method shown in FIG. 25, closure strip 318, alreadyfolded in half, is fed across an angled roller 356 and between thelongitudinal edges 358 of bag film 254 as the film is folded withincollar 326. A pair of heated sealing rollers 360 continuously seals theedge regions of the bag film to the overlapping closure strip. Noinsulating rail is necessary as the loop material of the closure strip,which in this case is sufficiently wide to extend across the entiresealing region, inhibits the bonding of the opposing inner surfaces ofthe closure strip (as discussed further below with respect to FIGS. 36and 37). After passing through edge sealing jaws 342, the folded edge362 of the bag film is trimmed away along line 364, leaving the ends ofthe pouches opposite the closure strip open for receiving materials tobe packaged. The series of pouches may then be spooled into a roll forsale or later filling.

FIG. 26 shows a method of making bags from two separate sheets of bagfilm and the above-described bag closure strip. Upper and lower plasticfilms 368 and 370, respectively, are unspooled continuously, with eithera pre-folded closure strip, or pre-engaged hook and loop strips 372, fedbetween them as shown. An insulating rail 374 extends between the hookand loop strips, temporarily disengaging the hooks from the loops, asthe hook and loop strips are each permanently welded to respective innersides of the plastic films between two rotary sealing rolls 376 (onlythe upper roll is shown). The parallel films and fastener strips arethen welded together at spaced intervals by transverse heated sealingjaws 378, forming side seals between adjacent bags which are then filledfrom their open ends (not shown) and closed by upper and lower sets ofsealing jaws 380. This process is also useful, for instance, for forminga series of pre-made bags to be rolled or stacked for later filling.

The bag 382 formed by this process has four side seals 384, as shown inFIG. 26A, along with closure 372. The side seal 384 adjacent andparallel to closure 372 is ripped off to open the bag and expose theclosure. In another embodiment (not shown) the side seal 384 adjacentand parallel to closure 372 is omitted, along with the upper set ofsealing jaws 380 in FIG. 26, and a folded closure strip (e.g., strip 318of FIG. 25) is inserted in place of separate strips 372, with the foldof the closure strip pointing outward toward the adjacent side of thecontinuous films. In another embodiment, producing an “inverted” closurearrangement similar to that shown in FIG. 36, the folded closure stripis fed between the plastic films with its fold extending away from theadjacent edge of the films.

The closure strip also provides, in some instances, a broad, externalbag surface for carrying text, logos or other marketing indicia. In FIG.27, a produce bag 400 is formed generally of loosely woven plastic meshto provide unobstructed air circulation and a clear view of the qualityof the enclosed produce. The plastic mesh is formed into a bag with afold at the bottom edge 402 and is either sewn or thermally fused alongits two sides 404, one of which may remain open until the contents areinserted. A wide closure strip 406 sewn or welded to the plastic bagmesh at the upper end of the bag provides a solid surface 408 printedwith appropriate marketing indicia and information, which may be appliedto the closure strip either before or after it is attached to theplastic mesh forming the rest of the bag. In other instances, the broadouter face of the closure strip provides a support for securing adhesivelabels (not shown) printed with such information. In the example shown,the closure strip is thermally welded to the plastic mesh in regions 410(while an insulating rail, not shown, is disposed between the innerclosure strip surfaces to prevent permanent bonding between the sides ofthe closure strip, as discussed above). For convenient handling, aC-shaped slit 412 is cut through both sides of the closure stripoutboard of its hook and loop bands, to form a carrying handle. In otherapplications, air circulation holes may be provided through the closurestrip sides, as necessary.

As shown in FIG. 28, closure strip 406 is of similar construction to theclosure strip of FIG. 1, but with some modification. Notably, theoverall width of closure strip 406 is about 6.2 inches, with a fastenerband separation distance W_(D) of about 3.9 inches, providing sufficientwidth for printing with the closure edges either outboard or inboard ofthe plastic bag mesh. The width W_(E) of both the hook and loop bands106 and 104, respectively, is about 0.75 inch, with ⅜ inch wide outeredge regions having thickened weld zones 414.

The detail of the center features of the closure strip is shown in FIG.29. Grasping rib 416 is offset slightly from the centerline 418 (i.e.,the midline between the hook and loop bands), such that when the closurestrip is folded, the grasping rib will be biased to lie on apredetermined side of the fold, avoiding variability in hook/loop bandalignment caused by the fold line fluctuating between the two sides ofthe rib. Rib 416 has both a width W_(F) and a height H_(F) of about 1/32inch, and is immediately adjacent a shallow groove 420 extending alongthe length of the closure strip, of a width W_(G) of about 1/32 inch anda depth, d_(G), of about 0.002 inch. Groove 420 provides some space forrib 416 with the closure folded at centerline 418. Spaced apart from therib and groove are tear control features. These include a continuousrip-stop rib 422 of height H_(H) of about 0.002 inch immediatelyoutboard of a continuous tear-propagation groove. Two preferredtear-propagation groove profiles are shown. On the left of FIG. 29,groove 424 a is of square profile with sharp bottom corners forconcentrating stress during tearing. On the right of FIG. 29, groove 424b is of triangular profile with a single, acute corner at its center forconcentrating stress. For reasons explained above, to form this patternof features the mold roll is preferably equipped with a single plate orring of width W_(J), having a contoured outer surface for forming all ofthe features shown. The nominal thickness of the closure base, t_(b), isabout 0.006 inch in this instance, but for different applications willbe selected between about 0.004 and 0.030 inch.

As shown in FIG. 30, the thickened weld zones 414 near the edges of theclosure strip extend a distance d_(w) of about 0.012 inch from the baseof the closure strip (giving these areas, which have a width W_(K) ofabout 0.120 inch, an overall thickness of about 0.018 inch). Withoutadjusting the profile of the extrusion die or otherwise varying theamount of entering resin along the length of the nip as the closurestrip is formed, the practical maximum thickness and width of weld zones414 will depend on the flow properties of the resin as well as thepressures and temperatures involved. Thickening the closure strip in theareas intended to be welded to other bag materials provides more resinavailable for flow and bonding during welding. In addition, the greaterclosure strip mass absorbs more heat and helps to keep the insidesurfaces of the closure strip base from being welded together. Thickermaterials are also less sensitive to fluctuations in welding conditions,enabling more consistent bonding.

For some applications, the closure strip provides loop-engageable hookelements on the outer surface of the bag, such as for attaching thepackaged product to a display or other support surface. For example,FIG. 31 shows a closure strip 426 at the upper end of a bag 428, havinga band 430 of molded hook fastener elements extending from its outersurface and exposed for engaging loop fibers. The closure strip mayinclude a grasping rib 132 as shown, and be configured to tear aboveband 430, such that the outer hooks remain on the opened bag.Alternatively, the closure strip may be configured to tear between band430 and the top edge of the bag film, in which case the grasping rib maybe unnecessary. The hooks of band 430 are useful, for instance, forhanging bag 428 from a display rack covered with loop material. Forstringing multiple bags together, a mating band of loops (not shown) maybe provided elsewhere on the outer surface of the bag, such that band430 of each bag engages the exposed loop band of an adjacent bag of thestring. FIG. 31 also illustrates an example of the weld-insulating loopmaterial arrangement discussed below with respect to FIGS. 36 and 37.

Optionally, closure strip 426 may include an outer band 432 of loopmaterial, extending from a side of the bag opposite the exposed band 430of hooks, for securing bags together in a stack. In another embodiment(not shown), the closure strip has an exposed band 432 of loops, but noexposed band 430 of hooks, and is hung thereby from a display rackhaving extending hook elements.

FIG. 32 shows a machine arrangement for producing closure strip 426 ofFIG. 31. A first resin 434 is extruded into a nip between a hook-formingmold roll 154 and a smooth pressure roll 156, along with loop material104 to form the primary loop band of the closure and, optionally, loopmaterial 432 to form the secondary (i.e., outer) loop band of theclosure. The cooling resin travels with the mold roll to a second nipbetween roll 154 and a secondary hook-forming mold roll 436, where it isjoined by a second flow of resin from extruder 438. The flow of resinfrom extruder 438 is much narrower than the resin traveling on roll 154,and is only applied in specific strips corresponding to the secondary(i.e., outer) hook bands formed on the closure strip. The resin fromextruder 438 is forced into hook-forming cavities in roll 436 by nippressure, and cools as the closure strip travels on the surface of roll436 until the secondary hooks are pulled from their cavities at roll440. Thus, the primary hook band 106 and the secondary hook band 430 areformed by rolls 154 and 436, respectively, and are, in someapplications, formed of different resins. As will be readily understoodfrom this example, other machine configurations will produce similarproducts. For example, the upstream mold roll may be employed to moldthe secondary hooks and closure base, with the downstream mold roll(i.e., the upper mold roll in FIG. 32) forming the primary hooks. Insuch case, the primary loop material 104 would preferably be introducedagainst roll 156.

Referring now to FIGS. 33 and 34A, pouch 442 includes a closure strip444 sealed along its two edges to bag film 446 with welds 330. Along itslower edge, the closure strip is welded on its outer face; at its upperedge it is welded on its inner face. In the illustrated embodiment,closure 444 differs from the closure 100 of FIG. 1 in that its tear rib132 extends from the face opposite the face on which its loop and hookbands 104 and 106, respectively, are carried. Additionally, rib 132contains a pull cord 320 as described above with respect to FIGS. 22–24.Rib 132 is formed in a corresponding groove in the pressure rollopposite the hook-forming mold roll in a Fischer-type process, with pullcord 320 introduced to the resin of the closure strip in the groove.Located on the inside face of the pouch as shown, pull cord 320 of rib132 is torn through the entire thickness of the closure strip base as itis pulled outward (in the direction of arrow “G” in FIG. 34A) to openthe pouch. Alternatively, rib 132 may be located on the same side of theclosure strip as the hook and loop bands (as in strip 100 of FIG. 1),with appropriate tear features extending along either side of the rib tofacilitate tearing of the closure strip, even without an embedded pullcord 320. In yet another embodiment (not shown), pull cord 320 is simplydisposed at the inner face of the closure strip (without an enclosingbase thickening or rib) and is pulled through the base in the directionof arrow “G” to open the pouch. Such a configuration is produced byintroducing the pull cord to the resin in the molding nip in aFischer-type process, on the pressure roll side of the resin, without arib-forming groove in the pressure roll.

As shown in FIG. 33, a c-shaped pull tab 448 is formed at one edge ofthe pouch by die cutting the outline of the pull tab through the rib 132and base of the closure strip 444 within a non-sealed region 450 withinthe side seal 452 of the pouch, without cutting through the bag filmbehind the closure strip. Because the closure strip is not bonded to thebag film (forming the back side of the pouch) within region 450, the cutpull tab is free to be grasped and pulled across the face of the pouchbetween the hook and loop bands of the closure strip, opening the pouchas shown in FIG. 34B. Alternatively, a hole may be provided through thelayer of bag film at 450, thereby leaving tab 448 exposed for grasping.Lettering 454 is shown in FIG. 33, printed on the exposed face of theclosure strip to indicate the location of the pull tab. As an alternatemeans of exposing the pull cord to be grasped, in another embodiment(not shown) a narrow width of closure strip 444 containing pull cord 320is left extending beyond the edge of the bag film, exposed to be pulledthrough side seal 452 and across the face of the pouch. Seal 452 may beconfigured as a peelable weld if necessary to enable the grasping rib orpull cord to be pulled through the seal without breaking.

After being opened, pouch 442 may be closed by folding over the upperedge of the pouch such that the hook and loop bands 106 and 104 of theclosure strip 444 overlap and engage, as shown in FIG. 34C. Re-openingthe pouch entails simply disengaging the touch fastening and unfoldingthe pouch top.

To form pouch 442, closure strip 444 is first sealed along what willbecome its lower edge to one edge of a continuous sheet of bag film. Theclosure/film combination then proceeds through the pouch-forming processknown in the art, in place of the bag film alone. As a final step beforeadjacent pouches are severed from one another, the pouches are filledthrough their upper ends before the upper weld 330 is formed between theclosure strip and the bag film, to seal the pouch. Also note that thisclosure strip arrangement has the advantage that the loop and hook bands104 and 106 of the closure strip do not generally come into contact withthe pouch contents, making such an arrangement particularly applicableto pouches containing fibrous or similar materials which may becomeembedded in the hook or loop bands and decrease the effectiveness orcosmetic appeal of the closure over time. In another sequence, notillustrated, the closure strip is sealed to the film after the bag filmis center-folded.

The closure strip is configured, in some cases, to be folded over uponitself multiple times after opening to form a substantially water-tightseal. For example, the closure strip 456 of home dry-cleaning bag 458 ofFIGS. 35A–35D is of sufficient width, as compared to the placement ofits loop and hook bands 104 and 106, so as to be readily folded overtwice after opening, to engage the hook and loop bands to form areleasable closure (FIG. 35D). As with the embodiment of FIG. 33, thehook and loop bands of the closure remain separated from the bagcontents as they are carried on the outside of the bag. To effect theoverlap of the hook and loop bands when the bag top is folded overtwice, the loop band 104 is disposed much closer to the grasping rib 132at the upper edge of the bag than is the hook band 106. The appropriaterelative dimensions required to effect such an overlap will be apparentfrom the sequential illustration of FIGS. 35B–35D. As the two separatedsides of closure strip 456 are folded over together twice, two distinctfolds 460 a and 460 b are formed. The ability of these folds to form aseal against gas or liquid penetration will depend upon the tightness ofthe folds and the viscosity of the fluid to be sealed, among otherthings, but such folds will form effective seals for many applications,such as in bags for home dry-cleaning kits as described in U.S. Pat. No.5,238,587, the contents of which are incorporated herein by reference.For such applications in which the bag does not have to remain sealedprior to use, the upper edge of the bag containing rib 132 may besevered from the bag during bag production, such that the bag is sold inan open condition as in FIG. 35B. As another alternative, the closurestrip may be in the form of two separate strips, a hook strip and a loopstrip, each strip forming one side of the closure and being separatelywelded to the bag film.

For some applications, the bag closure is welded between two separatefilm sheets to form a bag. FIG. 36 shows one such bag closure 462 weldedto bag side sheets 464 a and 464 b, forming what we call an “inverted”closure. The side sheets of the bag extend beyond the closure strip andare themselves welded together to form the upper edge 466 of the bag.After the closure strip has been bonded to the bag sides, and the sideedges of the bag sealed (not shown) the bag is filled from its otherend, in the direction of arrow “J”, which is then sealed to close thebag. To initially open the bag, edge 466 is pulled, tearing the bag sidesheets along perforations 468. Next, the closure strip is forced openand the closure strip web is pulled in two along a tear groove 470 atthe closure strip fold. To reclose the bag, the loop and hook bands 104and 106 of the closure strip are simply pressed together.

The welding pattern shown in FIG. 36 provides the anti-peel advantagesdiscussed above, as the inner edge of the loop side of the closure stripremains unbonded to bag side sheet 464 b. One method of forming such aweld pattern is shown in FIG. 37, in which closure strip 462 issimultaneously welded to both bag side sheets 464 a and 464 b by heatedjaws 472 and 474, respectively. Advantageously, loop material 104 isarranged on the folded closure strip to overlap both inner and outerclosure strip weld zones, inhibiting any permanent welding together ofthe sides of the closure strip. For applications in which a small amountof bonding between the inner faces of the closure strip is acceptable(or desirable), a chilled jaw 476 against the loop side of the bagadjacent the inner weld zone prevents any undesirable bonding of theinner edge of the loop side of the closure to bag side sheet 464 b.

As an alternative to applying the closure strip to the bag film as thebag film is formed into bags, the closure strip may be pre-applied tothe bag film, and both spooled together into rolls. Such configurationsare particularly useful in the subsequent formation of bags on standardbag-making machines not equipped for the application of closure strips.For example, FIGS. 38A through 38C show spooled or rolled film productsconsisting of a continuous sheet of thin plastic film permanently bondedto one or more continuous lengths of closure products. In FIG. 38A,closure strip 318 is centered upon the bag film 254, such as for formingbags with the process illustrated in FIG. 20. In FIG. 38B, closure strip444 is sealed along one edge of bag film 446 to form rolled product 482,such as for forming pouch 442 of FIG. 33. In FIG. 38C, separate lengthsof hook and loop products 484 and 486, respectively, are bonded toopposite edges of film 488 to form rolled product 490, which may be runthrough standard form/fill processes to incorporate resealable closuresinto longitudinal fin seals.

Referring to FIG. 39, bag 500 consists of a piece of polyethylene bagmaterial folded once to form the bottom edge 502 of the bag, joined to aclosure 504 to form the upper edge 505 of the bag, and permanentlysealed along the remaining two sides 506 and 508 by welding the materialof the front face of the bag to the material of the back face of thebag. Although illustrated as a flat bag, bag 500 may be constructed inother forms, such as a pouch with a lower pleated end for standing thepouch upright on its lower edge.

Referring to FIG. 40, to initially open the sealed bag, the upper edge502 is grasped in one hand 510 and the front face of the bag is graspedin the other hand 512, on either side of a frangible channel 514extending along closure 504. By only grasping or pinching the front faceof the bag with hand 512, and not the back face of the bag, pulling thefront face of the bag away from the upper edge places a high tensileload across channel 514, propagating a tear along channel 514 thatcreates an opening 515 into the bag.

As shown in FIG. 41A, the bag material of the back side 516 of the bagis welded to the back (i.e., non-fastening) side of the reclosableclosure 504 at 518. The bag material of the front side 520 of the bag iswelded to the closure along an edge region 522 of the front (i.e.,fastening) side of the closure 504. With the closure so attached to thebag material, and sealed along the sides of the bag (see FIG. 39), theclosure provides an airtight, liquid-tight seal at one end of the bag.

The front face of closure 504 carries a strip 524 of fibrous loops, innon-woven form and partially embedded within the base resin of theclosure, and a strip 526 of hook-shaped fastener elements molded out ofresin of the base in rows extending along the length of the closure.After being initially opened by pulling apart the closure along groove514, the bag may be reclosed by folding its upper edge about the openingcreated by tearing the closure, releasably engaging the strip 524 ofloops with the strip 526 of hooks (FIG. 41B).

Referring to FIGS. 42 and 43, closure 504 is a strip of polyethylenehaving an overall width “W” of about 1.5 inches (38 millimeters) and anominal thickness “T” of about 0.004 inch. Loop band 524 has a widthw_(L) of about 0.5 inch (12 millimeters), and hook band 526 a widthw_(H) of about 0.375 inch (9.5 millimeters). The hook and loop bands areseparated by a distance w_(c) of about 0.29 inch (7.4 millimeters), atthe center of which is formed groove 514 that is 0.002 inch (0.05millimeter) deep and extends over a width w_(G) of about 0.036 inch (0.9millimeter). Thus, at groove 514, the closure has a reduced thicknessT_(G) of only about 0.002 inch (0.05 millimeter). The remaining width ofthe closure strip forms an open weld flange 527 outboard of the band 526of fastener elements for welding or otherwise attaching the closurestrip to the bag material. Extending in many parallel rows on eitherside of groove 514 throughout the area of the closure separating thehook and loop bands is an array of rip-stop features 528 unitarilymolded with the front face of the closure strip.

As shown in FIG. 44, the rip-stop features 528 are hump-shapedprotrusions that are longitudinally offset from the protrusions ofadjacent rows to form a checkerboard matrix of bumps for limiting tearpropagation from the tear channel. With a height of only about 0.006inch (0.15 millimeter) from the face of the closure, the rip-stops 528are substantially shorter than the engageable hook elements, such thatthe rip stops do not interfere with the engagement of the fastenerelements or the folding of the bag after opening.

Referring to FIG. 45, bag 500′ is of construction similar in all aspectsto that of above-described bag 500, except for the configuration of theattachment of the bag material of the front face 520 of the bag to thelower edge of closure strip 504. In this case, the weld zone 522 betweenthe bag material and the closure strip is spaced apart from the freeedge 530 of bag material 520, such that the distal edge of the bagmaterial forms an exposed, cantilevered pull flap 532 extending alongthe entire width of the bag. Thus, to open bag 500′ by bursting theclosure strip along its tear groove, one hand grasps the upper edge 505of the bag as with bag 500, but the other hand, rather than pinching thebroad expanse of bag material forming the front face, grasps theconvenient pull flap 532. The construction of bag 500′ may beparticularly advantageous where incidentally pinching the contents ofthe bag is to be avoided, for instance.

Another pull flap configuration is illustrated in FIG. 46. In this case,the upper edge 534 of the front face bag material is securely welded tothe front face of closure 504, without leaving a graspable end exposedalong its entire length, but the bag material is pre-cut to form anextending tab 536 of bag material at the center of the bag.

Referring to FIG. 47, bag 550 is of similar construction to the bagsalready described, except that its closure 552 has, in place of thefrangible channel or groove, a tear rib 554 of substantially greaterthickness than the base of the closure. Tear rib 554 extends along theclosure midway between the loop and hook bands and is adapted to begrasped at one end 556 and pulled to separate the tear rib from the restof the closure material along the width of the bag.

To enhance the graspability of the end 556 of tear rib 554, two featuresare formed in the bag and closure material adjacent the tear rib end,preferably by cutting methods. First, a notch 558 is formed in the bagmaterial forming the back side of the bag, immediately behind tear ribend 556, big enough to enable the grasping of the tear rib endindependent of the bag material but not extending through the entirewidth w_(s) of the edge seal (if the integrity of the unopened bag sealis to be maintained). Second, two slits 560 a and 560 b are made throughthe base of closure 504 and extending at an angle from the bag edge 562to, but not through, tear rib 554. The base of the closure between slits560 a and 560 b thus forms a pull tab 564 with a wide distal end, freeof any bag material, for improved graspability.

Referring to FIG. 48, another bag-making process features applying theclosure strip in discrete lengths across the bag film (i.e.,transversely), instead of longitudinally as earlier described. Bag film254 is unspooled from a roll 570 and onto filling tube 256 over guideforms 262, as described above with respect to FIG. 15. However, in thiscase individual lengths 572 of closure strip are advanced across the bagfilm and permanently attached to the film, such as by thermal welding,at bag-length intervals. Preferably, the attachment of the closurestrips occurs while the bag film is paused between film advancements,such as while a bag at the lower end of the tube is being sealed andsevered. In this manner, inclusion of the closure strips requires verylittle modification in the bag-making apparatus. As an alternative toattaching the closure strips 572 to the bag film 254 as it is unrolledinto the bag-making apparatus, roll 570 may be provided with the closurestrips pre-applied at proper intervals.

Referring also to FIG. 49A, the closure strip 572 is in one examplefolded over upon itself as attached to the bag film 254, with the bandsof hooks and loops engaged to hold the closure in its folded condition.One side of the closure strip is welded to the bag film in areas 574,while the other side of the closure strip is left unattached untilwelded to an opposing surface of the bag film below the filling tube(e.g., by sealing bars 264). Thus, closure strip 572 is positioned atone end of the final bag, with its fold either directed outward orinward as desired. The sides of the bag may be joined to form theadjacent end edge of the bag to form an additional end seal. Ifnecessary to hold the closure strip in its folded condition as the bagfilm is advanced onto the filling tube, the ends of the closure stripmay be tacked together.

An alternative closure strip configuration is shown in FIG. 49B. In thiscase, the closure strip 572′ is supplied as two separate fastenerstrips—a loop strip 576 and a hook strip 578—that are engaged to eachother along their length. Both fastener strips are permanently attachedto bag film 254 along weld lines 574, on either side of a tear line 580(e.g., a row of perforations or a continuous score) in bag film 254.Closure strip 572′ may be positioned in the final bag at any point alongthe length of the bag, which is opened by bursting tear line 580 andseparating the loop and hook bands of fastener strips 576 and 578. Thebag is reclosed by pressing the hook and loop bands back together.

Referring to FIGS. 50A and 50B, closure strips 582 and 584 areadvantageously provided with peelable seals 586 that act as secondaryclosure means. Peelable adhesives are well known in the industry, andprovide an air and liquid tight seal that is relatively easy to openwithout tearing the underlying substrate. In some cases, seal 586 is ofa material which becomes effectively non-tacky when initially opened. Inother cases, seal 586 is of a material which retains its tackiness so asto continue to provide some sealing when the bag is reclosed. In closurestrip 582 (FIG. 50A) the peelable seal 586 is located inboard of theprimary hook and loop closure 588, so as to protect the loops andfastener elements from contamination from bag contents. In closure strip582′ (FIG. 50B) the peelable seal 586 is located outboard of the primaryhook and loop closure 588 and must be opened to access the primaryclosure. The peel seal may be formed by applying a peelable adhesive,such as a pressure sensitive adhesive, to the front face of the closurestrip. In some cases, the adhesive is applied in two discrete regions onthe face of the strip, such that the adhesive of the two regions comestogether to form the seal. Such peelable seals can provide a higherpantry life (i.e., a longer useful life after the bag has been initiallyopened) for the bag contents.

Referring to FIG. 51, a closure strip 590 has mating bands ofhook-shaped fastener elements 592. In one band, extending from one side594 of the closure strip, the fastener elements all face to the left,while from the other side 596 of the closure strip the fastener elementsall face to the right. As the bands of fastener elements 592 are pressedfurther together from the position shown, the tips of the hook-shapedfastener elements interlock to engage the two bands of elements. Whenpulled apart, the flexible tips extend to clear the tips of the otherband of elements and then snap back to their original hook shape. Thisis one example of what is known in the closure industry as“self-engaging” fasteners—those in which the engaging fastener elementsare of a similar structure. Other forms of self-engaging fastenerelements include mushrooms, for example, such as the “DUAL-LOCK”fastener product marketed by Minnesota Mining and Manufacturing, Inc.With self-engaging hook-shaped fastening, we prefer to mold the hooks tohave a greater thickness “t_(h)” than the spacing “s_(r)” betweenadjacent rows of elements (as shown in FIG. 52), such that the bandscannot be separated by moving one side of the closure strip laterallyacross the rows of fastener elements of the other side of the closurestrip. The CFM-15 and CFM-29 hook shapes marketed by Velcro USA inManchester, N.H., can be useful for self-engaging fasteners. Thehook-shaped fastener elements should be spaced along their rows so as toprovide sufficient clearance for the tips of a mating row of hooks toextend between adjacent hooks of the row. The optimal spacing willdepend upon the selected hook shape and the strength of engagementdesired. With mating arrays of mushroom-type fastener elements, themushroom density of the opposing arrays should be different to avoid“dead-heading” the mushrooms (i.e., forcing the mushroom heads to deformrather than causing their stems to bend). One array may have, forexample, a fastener element density on the order of about 50 to 200fastener elements per square inch, while the density of fastenerelements in the other array is of the order of about 500 to 2000.Optimal density matches will depend upon the desired engagement anddisengagement loads, among other things. Self-engaging bands of fastenerelements may be substituted for the loop and hook bands of any of theabove-described closure strips to form self-engaging closures forvarious applications.

Preferably, whether hook and loop bands or self-engaging fastener bandsare employed, the mating bands of the closure are advantageouslyconfigured to be engaged with a very low engagement force. We measureengagement force by measuring the facial load required between matinghalves of a one-inch long length of closure strip to engage the closure.Disengagement peel force is measured as the load required to peel such aone-inch strip of closure apart. The closure can provide anadvantageously low engagement force of, for instance, less than aboutone pound over a lineal inch of the closure, and a low disengagementpeel force of less than about two pounds per lineal inch.

Materials other than polyethylene, such as polypropylene, polyester,nylon, and other thermoplastics and their co-polymers, may be employed.For example, laminated or co-extruded bag films can have inner surfacesof a material weld-compatible with the material of the closure base, andan outer surface of a material chosen for other properties, such asdurability or impermeability.

As evident from the embodiments described above, these closure stripsare useful in many packaging applications, for providing areadily-engaged releasable closure that does not require perfectalignment during closing. The closures are useful for packaged fooditems, such as cookies, candy bars, and even produce, and may be locatedat one sealed end or along a longitudinal seam of the package. By “bag”,we mean to include all packages with flexible sides, including but notlimited to standable pouches and flexible cartons.

Other bag and closure constructions and bag-forming methods to which theabove features are applicable are disclosed in our U.S. Pat. No.6,202,260 and our provisional U.S. patent application Ser. Nos.60/159,489, 60/228,819 and 60/231,377 (filed Oct. 14, 1999, Apr. 16,1999 and Sep. 6, 2000, respectively), the entire disclosures of whichare hereby incorporated by reference as if completely set forth.

The contents of the following applications are all incorporated hereinby reference as if fully set forth: U.S. patent applications Ser. No.09/293,257 filed Apr. 16, 1999 and WO US99/26261 filed Nov. 5, 1997,designating the United States among others.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention. Forexample, it is to be noted that many features disclosed here areapplicable to attaching the closure during bag making as well as topre-applying the closure. Accordingly, other embodiments are within thescope of the following claims.

1. A reclosable bag comprising: a bag body having two opposing sidewalls joined along three edges to form therebetween a pouch having anopen end; and a closure strip permanently attached to the two side wallsof the bag body along the open end, the closure strip comprising asheet-form resin substrate having a front face and a back face; an arrayof loop-engageable fastener elements with stems integrally molded withand extending from the front face of the substrate and forming adiscrete band of fastener elements extending longitudinally along thelength of the closure strip; and a loop strip carried on the front faceof the substrate and forming a discrete band of engageable loopsextending along the length of the closure strip and spaced apart fromthe band of fastener elements, the loop strip arranged to be engaged bythe array of fastener elements to releasably retain the bag in a closedcondition; wherein the substrate of the closure strip defines at leastone frangible region extending longitudinally along the length of theclosure strip between the band of loops and the band of fastenerelements, for tearing the substrate between the loops and the fastenerelements to open the bag, the frangible region comprising an embedded,longitudinally continuous filament adapted to be torn from the closurestrip to tear the substrate along the frangible region.
 2. The bag ofclaim 1 wherein the filament is fully enclosed within a longitudinal ribextending from the back face of the substrate of the closure strip anddisposed inside the bag.
 3. The bag of claim 1 wherein the filament hasan end attached to a pull tab extending from one edge of the bag.
 4. Thebag of claim 1 wherein the bag defines a slit through an edge region ofthe bag but not extending into the interior of the bag, the slitdefining a graspable pull tab within said edge region and containing anend of the filament.
 5. The bag of claim 1 wherein the fastener elementshave distal ends integrally molded with their stems and the front faceof the substrate.
 6. A reclosable bag comprising: a bag body having twoopposing side walls joined along three edges to form therebetween apouch having an open end; and a closure strip permanently attached tothe two side walls of the bag body along the open end, the closure stripcomprising a sheet-form resin substrate having a front face and a backface; an array of loop-engageable fastener elements with stemsintegrally molded with and extending from the front face of thesubstrate and forming a discrete band of fastener elements extendinglongitudinally along the length of the closure strip; and a loop stripcarried on the front face of the substrate and forming a discrete bandof engageable loops extending along the length of the closure strip andspaced apart from the band of fastener elements, the loop strip arrangedto be engaged by the array of fastener elements to releasably retain thebag in a closed condition; wherein the front face of the closure stripforms an outer surface of the bag, with the bands of loops and fastenerelements carried on said outer surface of the bag.
 7. The bag of claim 6wherein both the band of loops and the band of fastener elements aredisposed on a front side of the bag, such that the fastener elementsengage the loops when an adjacent edge of the bag is folded over.
 8. Thebag of claim 7 wherein the substrate of the closure strip defines afrangible region between the bands of loops and fastener elements, thefrangible region running along one side of the bag and configured to betorn to open the bag.
 9. The bag of claim 8 wherein the frangible regionis configured to be torn by applying a transverse tensile load acrossthe frangible region.
 10. The bag of claim 9 wherein the frangibleregion of the substrate is weaker with respect to a transverse tensileload than the side walls of the bag and the attachment between the sidewalls of the bag and the bag closure.
 11. The bag of claim 6 wherein thefastener elements have distal ends integrally molded with their stemsand the front face of the substrate.
 12. A reclosable bag comprising: abag body having two opposing side walls joined along three edges to formtherebetween a pouch having an open end; and a closure strip permanentlyattached to the two side walls of the bag body along the open end, theclosure strip comprising a sheet-form resin substrate having a frontface and a back face; an array of loop-engageable fastener elements withstems integrally molded with and extending from the front face of thesubstrate and forming a discrete band of fastener elements extendinglongitudinally along the length of the closure strip; and a loop stripcarried on the front face of the substrate and forming a discrete bandof engageable loops extending along the length of the closure strip andspaced apart from the band of fastener elements, the loop strip arrangedto be engaged by the array of fastener elements to releasably retain thebag in a closed condition; wherein the substrate of the closure stripcarries printed indicia thereon and visible from outside the bag. 13.The bag of claim 12 wherein the fastener elements have distal endsintegrally molded with their stems and the front face of the substrate.14. A reclosable flexible package comprising: a flexible plastic film ofwall thickness less than about 0.005 inch including a reclosable,elongated closure including a band of hook-engageable loops and a bandof hooks adapted to be facially engaged to close the package; whereinthe band of hook-engageable loops and the band of hooks are constructedto be usefully engaged upon application of a uniform facial engagementforce of less than about one pound per lineal inch of closure and to beopened by a transverse peel force of less than about two pounds perlineal inch of closure.
 15. The reclosable flexible package of claim 14,wherein the loops of the band of hook-engageable loops are constructedto individually interact with the hooks of the band of hooks to form afield of localized releasable fastenings to form a peel-open enclosure.16. The reclosable flexible package of claim 15, wherein the hooks havehook-shaped head portions extending laterally in one or more discretedirections.
 17. The reclosable flexible package of claim 16, wherein thehooks have hook-shaped head portions extending laterally in multipledirections.
 18. The reclosable flexible package of claim 15, wherein theband of hooks has a hook density greater than about 1,000 hooks persquare inch.
 19. The reclosable flexible package of claim 15, whereinthe band of hook-engageable loops comprises a non-woven web of entangledfibers.